Guides
How to do everyday jobs with PDFs, photos, numbers and passwords properly — what usually goes wrong, the steps that avoid it, and how to check the result.
- Why a PDF or image got bigger after compressing itCompressing a text PDF or an already-small JPG can make it larger. Why it happens, how to tell in advance, and what to do instead to get a smaller file.
- Why a form rejects your PDF even though it is under the size limitUpload portals reject PDFs for more than size: passwords, form fields, odd file names, the wrong file type and page limits. How to find the cause and fix it.
- Why the text in a PDF looks blurry and cannot be selectedBlurry, unselectable text means the PDF holds pictures of pages, not text. How to check, why it happened, and how to get crisp, searchable text back.
- Why your filled-in PDF form looks blank to someone elseYou filled in a PDF form, but the recipient sees empty boxes or the printout is blank. Why viewers disagree about form fields, and how flattening fixes it.
- Why your signature has a white box around it on a PDFA signature photo pasted onto a PDF covers lines and text with a white rectangle. Why JPG can't be transparent, and how to sign so only the ink shows.
- How to get a PDF under an upload limit (100 KB, 500 KB or 1 MB)Exam, job and government portals cap PDF uploads. How to shrink a PDF to fit a 100 KB, 500 KB or 1 MB limit, and what to try when it still will not fit.
- How to remove blank pages from a scanned PDFDuplex scanners and Word exports leave empty pages behind. How to spot them, remove them all in one pass, and stop them appearing next time.
- How to reverse the page order of a PDFScanned a stack face up and got the last page first? How to flip a whole PDF into the right order in one click, then fix any stray pages by hand.
- How to add a header or footer to every page of a PDFStamp a title, date, reference number or Confidential along the top or bottom of every PDF page, skip the cover page, and keep the text clear of the content.
- How to change the title a PDF shows in the browser tabA PDF opened in a browser can show a title like Microsoft Word - Document1 instead of its name. Why it happens and how to set a proper title and author.
- What does flattening a PDF mean, and when should you do it?Flattening turns form fields and their answers into ordinary page content. When it helps, when a portal requires it, and why you should keep an unflattened copy.
- How to read a PDF in dark modeMost PDF viewers ignore your dark theme. How to make a PDF dark with light text for night reading, what happens to photos, and when a viewer setting is enough.
- How to count the words in a PDFTranslators, editors and students often need a PDF word count. How to get one, why a scanned PDF counts as zero, and why two tools can disagree.
- How to make a PDF portfolio from your imagesTurn your best images into one PDF portfolio that opens anywhere: page order, page size, keeping under a file size limit, and bookmarks for each project.
- How to get editable text out of a scanned PDFA scanned PDF is a stack of pictures, so copying and searching do nothing. How to tell, how to run OCR on the pages, and how to check the text it produces.
- Why a PDF prints too small or gets cut off, and how to fix itBig white margins, text chopped at the edges, or a page shrunk into the middle of the sheet. What causes each printing problem and how to fix it.
- How to rotate a PDF permanently — so it stays the right way upFix sideways or upside-down PDF pages for good, rotate only the pages that need it, and understand why rotating in a viewer does not stick.
- How to turn PDF pages into images: JPG or PNG?Save PDF pages as pictures for slides, social media or image-only upload forms, choose between JPG and PNG, and pick a resolution that stays sharp.
- How to extract the images from a PDF at full qualityPull the original photos and graphics out of a PDF instead of screenshotting them, understand why some PDFs give nothing, and what to do then.
- How to turn photos of receipts and documents into one PDFCombine phone photos of receipts, forms and certificates into a single PDF for expenses or applications, with tips for clean, small, readable pages.
- How to convert a Word document to PDF — and keep it looking rightThe best way to turn a Word document into a PDF for each situation, why layouts sometimes shift, and how to make a small, searchable PDF to send.
- How to add bookmarks to a PDF so readers can jump to each sectionGive a long PDF a clickable outline in the reader's sidebar: when bookmarks help, how to add and edit them, and the order to do it in.
- How to print several PDF pages on one sheet of paperPut 2, 4 or more PDF pages on each sheet to save paper for handouts, slides and drafts, choose a layout that stays readable, and print it at the right scale.
- How to print a PDF in black and white — and save inkPrint colour PDFs in greyscale from any printer, make a black-and-white copy for print shops that charge by colour page, and keep charts readable in grey.
- How to fill in a PDF form — even one that isn’t fillableFill in a PDF form on a computer or phone without printing it, deal with forms that refuse to open or have no fields, and lock your answers before sending.
- A4 vs US Letter: the paper sizes, and how to convert between themThe exact sizes of A4, US Letter, Legal and the A series, which countries use which, why documents print badly on the other size, and how to convert a PDF.
- How to print a booklet from a PDF on an ordinary printerTurn any PDF into a folded, stapled booklet on a home or office printer: page order, the multiple-of-four rule, duplex settings, folding and stapling.
- How to get a table or bank statement out of a PDF and into ExcelTurn a table in a PDF — a bank statement, an invoice list, a price list — into a spreadsheet you can sort and add up, and check the result properly.
- How to add page numbers to a PDF — and get them rightNumber the pages of any PDF: where to put the numbers, how to skip a cover or start from a different number, and the order to do things in.
- How to compare two versions of a PDF and see exactly what changedSpot every added and removed line between two versions of a contract, policy or report, see what a comparison can't catch, and check drafts privately.
- What a PDF can reveal about you — and how to remove it before sharingPDFs carry author names, software, dates, comments and sometimes earlier versions. See what yours holds and clean it before sending it outside your organisation.
- How to read PDFs comfortably on a tablet, phone or e-readerMake small print on A4 and Letter PDFs readable on a smaller screen: crop the wasted margins, read at night without the glare, and handle two-column papers.
- How to watermark a PDF — draft, confidential or copyAdd a DRAFT, CONFIDENTIAL or COPY watermark to a PDF, choose a placement that is hard to crop out, keep the text readable, and know what a watermark cannot do.
- How to redact a PDF properly — and why black boxes don’t workBlack boxes don't remove text from a PDF. Learn where hidden text survives, how to redact a PDF so the words are really gone, and how to check it worked.
- How to merge PDF files into one — without uploading themCombine several PDFs into one document in the order you want, keep full quality, and avoid sending private files to an upload site.
- How to reduce PDF file size for email and upload limitsWhy some PDFs are huge, which ones shrink well, and how to get a PDF under an email or upload limit without making it unreadable.
- How to split a PDF or pull out only the pages you needSplit a PDF into several files, save every page separately, or pull a few pages into a new document — with page ranges explained.
- How to convert a PDF to Word — and what to expect from the resultTurn a PDF into an editable Word document, understand why layouts rarely survive perfectly, and what to do when a scanned PDF gives no text.
- How to sign a PDF without printing itAdd your handwritten signature to a PDF on a phone or computer, without printing, scanning or uploading the document to a signing service.
Images
- Why a website says your photo’s format is not supportedUpload forms reject photos that look like JPGs. Usually the file is really HEIC, WebP or AVIF, or renamed. How to check what a file is and convert it properly.
- Why an image goes blurry when you make it biggerEnlarging a small image spreads the same pixels further, so edges go soft. How far you can safely upscale, why DPI won't help, and what to do instead.
- Why two photos the same size in pixels have very different file sizesTwo 4000 × 3000 photos can be 2 MB and 8 MB. Detail, noise, format, quality and hidden metadata decide the file size. What each does and how to shrink it.
- What size should an email signature image be?Logos and headshots in email signatures often arrive huge, blurry or blocked. The pixel sizes and file sizes that work in Gmail and Outlook, and how to make them.
- LinkedIn banner size: how to make a background photo that fitsThe LinkedIn background photo is 1584 × 396 pixels, a 4:1 strip that your profile photo partly covers. How to crop one that fits and keep text in the safe area.
- How to set a full photo as your WhatsApp profile picture without croppingWhatsApp crops every profile photo to a square and shows it as a circle. How to fit a whole portrait or group photo inside it by padding, not cutting.
- How to resize your photo and signature for an online application formExam, job and visa forms ask for a photo and signature at exact pixels and between a minimum and maximum KB. How to hit both numbers without a rejected upload.
- Product photo sizes for Etsy, eBay, Amazon and ShopifySmall product photos cannot be zoomed and can lower a listing's quality. The sizes the big marketplaces recommend, why square works best, and how to prepare a set.
- What size should images be for a website?Pixel widths for hero images, blog images and thumbnails, sensible file sizes, and how to stop large photos slowing a page down without making them blurry.
- How many pixels do you need for a 4×6, 5×7 or A4 print?The pixel dimensions for sharp prints at common photo sizes, what 300 and 150 DPI mean in practice, and what to do when your photo is too small for the print.
- How to post a whole photo on Instagram with white bordersInstagram crops photos that are too wide or too tall. How to add white or coloured borders so the whole picture fits in a square, portrait or story frame.
- How to turn screenshots into a PDFCombine screenshots of receipts, chats, bookings or web pages into one tidy PDF, in the right order and at a readable size, without uploading them anywhere.
- Why are selfies backwards? How to flip a mirrored photoSelfies look backwards because the front camera shows a mirror image, and some phones save it that way. How to flip a selfie, and the setting that stops it.
- How to straighten a crooked photoA sloping horizon or a leaning building makes a good photo look careless. How to rotate by a fraction of a degree, then crop the corners so nothing looks tilted.
- How to find out when and where a photo was takenPhotos often carry the date, time, camera and even GPS location inside the file. How to read that EXIF data, why it is sometimes missing, and when not to trust it.
- How to print several photos on one pagePrint 2, 4, 6 or 9 photos on a single sheet for contact sheets, wallet photos, mood boards and school projects, with even spacing and nothing cut off.
- Why photos look blurry after uploading, and how to keep them sharpSharp on your phone, soft on WhatsApp, Instagram or Facebook. How apps resize and recompress photos, and the sizes and settings that keep them looking crisp.
- How to hide personal information in a screenshot before sharing itNames, account numbers and email addresses slip into screenshots. How to blur or crop them properly, why light blurring can fail, and what else to check.
- Does converting a JPG to PNG improve quality?No, and the file usually gets several times bigger. What converting really does, when PNG is still the right choice, and how to get better quality instead.
- How to watermark your photos before sharing them onlineAdd your name or website to photos to discourage reuse and show where they came from: placement, opacity, size, and what a watermark can and cannot do.
- How to make a round profile picture with a transparent backgroundCrop a photo into a clean circle for documents, slides and email signatures, keep the corners transparent, and frame the face so it looks right small.
- How to convert an SVG to a PNG at the right sizeTurn an SVG logo or icon into a sharp PNG for places that only accept pixel images, choose the export size, and fix missing fonts and images.
- How to turn a photo black and white — the three methods comparedConvert a colour photo to black and white, see why the method changes the result, and when high contrast makes photographed text easier to read.
- Why photos appear sideways — and how to fix them for goodA photo upright on your phone shows sideways on a website or computer. Here is why orientation data causes it, and how to rotate the picture permanently.
- PNG to JPG: what happens to a transparent backgroundConverting a transparent PNG to JPG fills the clear areas with a colour. Here is how to choose it, when to convert at all, and how much smaller the file gets.
- How to save a YouTube video's thumbnail at full resolutionGet the thumbnail image for any YouTube video or Short at the largest size available, understand the sizes, and use thumbnails responsibly.
- Image aspect ratios explained: 16:9, 4:3, 3:2, 1:1 and 9:16What aspect ratios mean, which one each screen, camera and platform uses, and how to crop a picture to a ratio without stretching it.
- JPG, PNG, WebP or AVIF: which image format should you use?What each image format is good at, which one to choose for photos, screenshots, logos and websites, and why converting never improves a picture.
- What DPI means — and when 300 DPI actually mattersDPI explained simply: why “send it at 300 DPI” is half an instruction, how many pixels a print needs, and what to do when you don't have enough.
- How to make a favicon for your websiteDesign a favicon that still reads at 16 pixels, create every file browsers and phones look for, and add it to your site so it actually shows up.
- Instagram image sizes, and how to stop Instagram ruining your photosThe sizes Instagram uses for posts, Stories and Reels, why uploads come out soft or cropped, and how to prepare pictures so they stay sharp.
- How to check a design works for colour-blind peopleAbout one man in twelve sees colour differently. How to test charts, interfaces and graphics for colour blindness, and the simple fixes that work.
- How to blur faces and number plates in a photo properlyHide faces, number plates, house numbers and screens in a photo so they cannot be recovered, check the result, and catch the details people usually miss.
- How to resize a photo to exact pixels and a file size limit in KBForms often demand a photo of exact pixels under a set number of KB. Crop, resize and compress in the right order to meet both limits without blurring.
- Why images download as WebP or AVIF — and how to open or convert themPictures saved from websites often arrive as .webp or .avif files older programs refuse. What these formats are, what opens them, and how to convert them.
- How to pick colours from an image and build a paletteExtract the main colours from a photo or logo as HEX, RGB and HSL codes, build a usable palette from them, and check which ones work for text.
- How to remove location and camera data from photos before sharingPhotos can carry GPS coordinates, dates and device details. See what yours reveal and strip that metadata without re-compressing the image.
- How to compress images without visible quality lossMake photos much smaller without a visible difference: which quality setting to use, when to resize instead, and which format fits which image.
- How to open and convert iPhone HEIC photosWhy iPhone photos arrive as .heic files that Windows and websites reject, how to convert them to JPG, and how to make your iPhone save JPGs instead.
- How to copy text from an image or screenshotGet editable text out of a screenshot, photo or scanned page with OCR — and the simple things that make the difference between clean and garbled results.
- How to make a passport photo at homeTake a passport or visa photo with your phone, crop it to the exact size at print quality, and avoid the mistakes that get applications rejected.
Calculations
- Why you can’t just average percentagesAveraging 90% and 60% gives 75%, but your real score may be 63%. Why percentages with different bases need a weighted average, and how to do it right.
- Why percentages don’t add up to 100% — and how to fix itA breakdown shows 33%, 33% and 33%, or 101% in total. Rounding, overlapping answers and different bases are why. How to present figures that add up honestly.
- Will a pay rise put me in a higher tax bracket and cut my take-home pay?A higher tax band only taxes the extra at the higher rate, so take-home pay still rises. How bands work, a UK example, and the real catches to watch for.
- Why your EMI calculation doesn’t match the bank’s figureAn online EMI result a few rupees or dollars off the lender's quote is normal. Fees, rounding, first-month interest and rate type explain most differences.
- Why 1.5% a month is not 18% a yearA monthly rate × 12 understates the yearly cost when interest compounds: 1.5% a month is about 19.6% a year. How to convert monthly and annual rates.
- Tip before or after tax? And does the discount come first?Should you tip on the pre-tax or post-tax total, or the price before a coupon? What's customary, how big the difference is, and when the order matters.
- Buy one get one free, 3 for 2, second half price: what discount is it really?Buy one get one free is 50% off only if you want two. The real percentage behind 3 for 2, second item half price and buy 2 get 1 half price, and how to compare.
- Celsius to Fahrenheit in your head: the shortcut and where it fails“Double it and add 30” is close for weather but wrong for fevers and ovens. How accurate it is, a better mental method, and reference points to remember.
- Square metres vs metres squared: area conversion mistakesWhy 1 m² is 10.76 square feet, not 3.28, why “2 metres squared” is ambiguous, and how to convert areas and volumes without the most common mistakes.
- Stones and pounds to kg: why 11.5 stone isn’t 11 st 5 lbA stone is 14 pounds, so decimal stones and stones-and-pounds are not the same. How to convert st and lb to kg and back, with worked examples and a quick check.
- Ton vs tonne: metric, short and long tons explainedA tonne is 1,000 kg, a US short ton 907 kg, and a UK long ton 1,016 kg. Which one a document means, why air conditioners are rated in tons, and how to convert.
- US vs UK pints, gallons and fluid ounces: why they differA UK pint is 568 ml, a US pint 473 ml. The UK fluid ounce is smaller, but there are 20 in a UK pint. The differences, why they exist and how to avoid mix-ups.
- Kilometres to miles in your head: three quick methodsMultiply by 5 and divide by 8, use the Fibonacci trick, or take 60%. How accurate each mental method is for distances and speeds, with worked examples.
- Troy ounce vs ounce: why gold is weighed differentlyGold and silver prices are per troy ounce, 31.1 g, not the 28.35 g ounce on kitchen scales. How to convert troy ounces to grams and check what a price means.
- kW vs kWh: the difference, and why your bill uses kWhkW is how fast energy is used; kWh is how much is used. How to turn appliance power into energy and cost, and how EV battery and charger figures fit together.
- Monthly vs annual subscription: when the yearly plan really savesAn annual plan is cheaper only if you keep it long enough. How to find the break-even month, compare weekly, monthly and yearly prices, and spot renewal traps.
- Reverse percentages: how to find the original numberA price after a 20% rise is 96, so what was it before? How to work backwards from a percentage increase, discount or tax, and the common mistake that gives 76.8.
- Percentage points vs percent: what is the difference?An interest rate rising from 4% to 5% is up one percentage point but 25 percent. Why the two are different, when to use each, and how headlines mislead with them.
- Markup vs margin: how to price for the profit you wantAdding 40% to cost does not give a 40% margin. The difference between markup and margin, a conversion table, and the formula to price for a target margin.
- How to calculate your salary increase percentageWork out your pay rise as a percentage, find the new salary from a percentage raise, compare it with inflation, and see what it means per month and per hour.
- Flat rate vs reducing balance interest: why 10% flat costs moreA 10% flat rate loan costs far more than a 10% reducing balance loan. A worked example, the equivalent reducing rate, and how to compare loan offers fairly.
- Loan prepayment: should you reduce the EMI or the tenure?After a part-prepayment, lenders ask whether to cut your monthly payment or the number of months left. A worked example shows which saves more interest, and when.
- How much car loan can I afford?Start from a monthly payment you can live with and work backwards to the loan amount. Worked figures for 3 to 6 years, the total cost, and the costs beyond the loan.
- How much deposit do you need to buy a house?5%, 10% or 20%? How the size of your deposit changes the monthly payment, the interest over the term and the rate you are offered, with a worked example.
- APR vs interest rate: which number to compareThe interest rate is what you pay on the balance; APR adds the fees. A worked example where an 8% loan has an APR of 10%, and how to compare loans fairly.
- The rule of 72: how long it takes money to doubleDivide 72 by the interest rate to estimate how many years money takes to double. How accurate the shortcut is, and how it works for inflation and debt.
- How much will a monthly investment grow to? (SIP returns explained)What 5,000 a month becomes after 5, 10, 15 and 20 years at 12%, why the later years add most of the growth, and what these projections can and cannot promise.
- How fixed deposit interest is calculated with quarterly compoundingWhy a 7% fixed deposit pays more than 7% a year, a worked example for 1,00,000 over five years, and how payout options and tax change what you receive.
- How to calculate overtime pay (time and a half, double time)Work out time-and-a-half and double-time pay from an hourly rate or a salary, with a worked weekly example, and check your payslip for the usual mistakes.
- Pro rata salary: how part-time and part-year pay is worked outA job advertised at 30,000 pro rata for 22.5 hours a week pays 18,000. How to calculate pro rata pay, holiday and part-year salaries, with worked examples.
- CTC vs in-hand salary: why 12 LPA is not 1 lakh a monthAn Indian job offer quotes cost to company, not what reaches your bank. What CTC includes, a worked example for 12 lakh, and how to estimate monthly in-hand pay.
- How to convert CGPA to percentageCBSE multiplies CGPA by 9.5, but universities use their own formulas. How each one works, a worked example, and what to write when a form asks for a percentage.
- What grade do I need on my final exam?Work out the final exam score you need for the overall grade you want, from your current grade and the exam's weight, with worked examples and the formula.
- Weighted vs unweighted GPA: what is the difference?Why one transcript can show a 3.5 and a 3.9 for the same student. How weighted GPA rewards honors and AP classes, a worked example, and what colleges look at.
- How to calculate age on a specific date (for exam and job eligibility)Exam and job notices set age limits as on a cut-off date. How to work out your exact age on that date, read born-between ranges, and avoid the leap-day traps.
- How to count the days between two datesCount days, weeks and months between two dates, decide whether to include the end date, and avoid the month-length and leap-year mistakes of counting by hand.
- Cat years to human years: how old is my cat?A one-year-old cat is roughly 15 in human years and a two-year-old about 24. The chart vets use, cat life stages, and what changes as your cat gets older.
- What is a healthy weight for my height?The healthy weight range for your height in kilograms and pounds, how it is worked out from BMI, and why it is a range rather than a single ideal number.
- BMI cut-offs for Asian adults: why 23 mattersFor people of South Asian, Chinese and other Asian backgrounds, health risks rise at a lower BMI. The 23 and 27.5 cut-offs, their origin and how to use them.
- Fever temperatures in Celsius and FahrenheitIs 37.8 °C a fever? What is 101 °F in Celsius? A body temperature conversion chart, where a fever starts, and how the thermometer site changes the reading.
- Knots to mph and km/h: how fast is a knot?One knot is one nautical mile per hour: 1.852 km/h or about 1.15 mph. A conversion table for boats, planes and wind, and why sailors and pilots still use knots.
- How to convert mpg to litres per 100 km (and back)Convert fuel economy between US mpg, UK mpg, litres per 100 km and km per litre, with tables, formulas, and why US and UK figures differ for the same car.
- Mbps vs MB/s: how fast will my download really be?A 100 Mbps connection downloads at about 12.5 megabytes per second, not 100. Bits versus bytes, download time tables, and why real speeds come in a little lower.
- How to measure a room in square feet and square metresMeasure a room's floor area, convert between square feet and square metres, handle L-shaped rooms, and add the right allowance when buying flooring.
- How many rolls of wallpaper do I need?Count wallpaper the way decorators do: by drops, not by area. A worked example, how pattern repeat changes the answer, and why to buy from one batch.
- Why sin(30) gives −0.988: degrees vs radians on a calculatorIf sin(30) does not give 0.5, your calculator is in radian mode. How to tell, how to switch, how to convert between degrees and radians, and when to use each.
- EST vs EDT, GMT vs UTC: time zone abbreviations explainedEST is not the same as EDT, and GMT is not quite UTC. What common time zone abbreviations mean, when daylight saving changes them, and how to avoid missed calls.
- How to calculate a discount, a sale price and a stacked offerWork out a sale price, the real saving from stacked discounts, an original price from a sale price, and whether a multi-buy is actually a bargain.
- Weekly, fortnightly or monthly loan payments: which costs less?How payment frequency changes the total interest on a loan, why the saving is small unless you pay more, and how “accelerated” fortnightly payments work.
- Order of operations: why 2 + 3 × 4 is 14, not 20The rules a scientific calculator follows — brackets, powers, multiplication and division, addition and subtraction — plus degrees versus radians and common errors.
- Currency conversion: the real rate, the bank's rate and the hidden feesWhat the mid-market exchange rate is, why your bank or card gives less, how to compare providers, and the card-terminal choice that costs travellers money.
- Height in feet and inches to centimetres, and backConvert a height between feet and inches and centimetres exactly, with a quick reference table and the mistakes that put conversions an inch out.
- Acres, hectares, square feet and local land units explainedConvert land and floor areas between acres, hectares, square metres and square feet, picture how big each one is, and handle local units such as ropani and cent.
- Running pace and speed: min/km, min/mile, km/h and mphConvert running pace to speed and back, switch between kilometres and miles, and work out a finish time for 5K, 10K, half marathon and marathon.
- Shoe size conversion: US, UK, EU and Japan — and why it variesConvert shoe sizes between US men's and women's, UK, European and Japanese systems, measure your foot properly, and understand why brands disagree.
- Engine cc, litres and horsepower: what the numbers meanConvert engine size between cc, litres and cubic inches exactly, see why horsepower can only be estimated from engine size, and decode hp, bhp, PS and kW.
- How to schedule a meeting across time zones without mistakesFind hours that suit people in several countries, avoid the daylight saving weeks that move meetings, and write invites nobody can misread.
- How to calculate percentage change — and the mistakes everyone makesThe percentage change formula with worked examples, why a rise and a fall of the same size are different percentages, and percent versus percentage points.
- How to add or remove VAT, GST or sales tax from a priceAdd tax to a net price, take it out of a gross price the right way, and see why subtracting the percentage gives the wrong answer — with worked examples.
- Compound interest explained, with real numbersHow compound interest works, how much compounding frequency really matters, the rule of 72, and why starting early beats almost everything else.
- How to convert hourly pay to an annual salary, and backTurn an hourly rate into a yearly, monthly or weekly figure and back again, avoid the four-weeks-a-month mistake, and compare job offers fairly.
- How much paint do I need? Measuring a room properlyMeasure a room, work out the wall area, allow for doors, windows and coats, and turn it into the right number of tins — with metric and imperial examples.
- How to calculate attendance percentage — and how many classes you can missWork out your attendance percentage, how many classes you can still miss above a 75% requirement, and how many you need to attend to get back above it.
- How to calculate an exact age in years, months and daysWhy dividing by 365 gives the wrong age, how to count years, months and days, what happens to 29 February birthdays, and how to find an age on a cut-off date.
- Dog years to human years: why the ×7 rule is wrongHow old a dog or cat really is in human terms, why size changes the answer, what a DNA study found, and a quick chart for small, medium, large and giant dogs.
- How much does it cost to charge an electric car?Work out the cost of a charge and the cost per mile or kilometre for an electric car, see why public rapid charging changes the picture, and compare with petrol.
- What goes into a mortgage payment — principal, interest, taxes and insuranceBreak a monthly mortgage payment into its parts, see how the deposit, rate and term change it, and why the total interest over 30 years is so large.
- UK take-home pay in 2026/27: how income tax and National Insurance are worked outHow UK income tax and National Insurance turn a salary into take-home pay in the 2026/27 tax year, with worked examples, the £100,000 trap and student loans.
- Recipe conversions: cups to grams, ounces, spoons and oven temperaturesConvert American, British and metric recipes: why cups to grams depends on the ingredient, US and UK pints, spoons, and oven temperatures in °C, °F and gas marks.
- How to turn a test score into a percentage and a letter gradeConvert any score such as 61/80 into a percentage and a letter grade, see common scores out of 80, and work out what you need on the final.
- How EMI is calculated — with a worked exampleThe EMI formula explained in plain words, a worked loan example, why early payments are mostly interest, and what a longer tenure really costs.
- How to calculate your GPA (and CGPA)Work out a credit-weighted GPA step by step, see why big courses count more, handle pass/fail courses, and combine semesters into a CGPA.
- What your BMI means — and what it cannot tell youHow BMI is calculated, what the WHO categories mean, the healthy weight range for your height, and the real limits of BMI for individuals.
- Why a 1 TB drive shows only 931 GB — and other storage numbers explainedNobody stole your storage: drive makers and computers count in different units. Here is the maths, plus MB vs Mbps and a quick conversion list.
Codes, passwords & text
- Why text shows ’, é or � instead of apostrophes and accentsGarbled characters like ’ and é appear when UTF-8 text is read with the wrong encoding. What causes it, how to fix the file, and how to stop it recurring.
- Why Word, Google Docs and online counters give different word countsThe same essay can show different word counts in Word, Google Docs and online tools. Hyphens, dashes, numbers, links and footnotes are counted differently.
- Why a website rejects your strong passwordLong random passwords can still fail a site's rules: maximum lengths, banned symbols, required character types or breach checks. How to find the rule.
- Why two texts look identical but a comparison says they differA diff flags lines that look the same. Trailing spaces, tabs, line endings, curly quotes and invisible characters are usually why. How to find and fix them.
- Why a printed barcode won’t scan — and how to fix itBarcodes fail when the quiet zone is missing, bars are too thin for the printer, contrast is wrong or the image was blurred. Causes and fixes in order.
- Why a random number generator keeps repeating numbersRepeats are normal in real randomness: pick 12 numbers from 1 to 100 and a repeat is a coin flip. When to worry, and how to draw without duplicates.
- Character count with spaces vs without spaces: which one to useForms, translators and social apps count characters differently. When spaces count, when they do not, how big the difference is, and how to get both figures.
- How to fix text typed with caps lock onTurn ALL CAPS or tHIS kIND oF tEXT back into normal sentences without retyping. Which case to choose, what to check by hand, and shortcuts in Word and Docs.
- How to remove line breaks from textText copied from PDFs and emails breaks every line in the wrong place. How to join the lines into proper paragraphs, keep real paragraph breaks, and fix split words.
- How to convert curly quotes to straight quotesSmart quotes from Word and Docs break code, CSV files, passwords and search. How to straighten them, plus em dashes and ellipses, and how to stop them being added.
- X (Twitter) character limit: what counts towards 280A post on X allows 280 characters, but links, emoji and some scripts count differently. What uses up the limit, what does not, and how to check a draft.
- Instagram caption and bio character limitsCaptions allow 2,200 characters and bios 150, but only the first line or two shows before more. How to fit the limits and write the part people actually see.
- How many pages is 1,000 words?About two pages single-spaced and four double-spaced, at 12 point. A words-to-pages table, what changes the answer, and how to estimate pages for any word count.
- Does the title count in an essay word count? What is includedTitles, references, quotations, footnotes and appendices: what usually counts towards an essay word limit, what usually does not, and how strict the limit is.
- Bold and italic text on LinkedIn and Instagram: the hidden problemsBold and italic letters in social posts are Unicode symbols, not formatting. How they work, why screen readers and search struggle, and how to use them sparingly.
- How to find and remove invisible characters in textZero-width spaces, byte-order marks and direction marks hide in copied text and break search, code and form validation. How to detect and remove them safely.
- How to make a QR code for Google reviewsTurn your Google review link into a QR code for the counter, receipts and table cards. Where to find the link, how to print it, and the review rules to follow.
- How to make a QR code for a restaurant menuPut your menu online, make a QR code for it and print table cards with no monthly fee. How to keep one code working when the menu changes, and keep it readable.
- What size should a QR code be when printed?The 10-to-1 distance rule, the practical minimum size, how the amount of data and error correction change it, and how colour, quiet zone and paper affect scanning.
- How to make barcodes for inventory and stock labelsInternal barcodes for stock, assets and storage bins do not need GS1 numbers. Which format to use, how to number items, and how to print labels that scan.
- How to make an ISBN barcode for a self-published bookAn ISBN barcode is an EAN-13 made from your 13-digit ISBN. Where the ISBN comes from, how to create the barcode, the price add-on, and where it goes on the cover.
- How long would it take to crack my password?From seconds to millions of years, depending on length, randomness and how a site stores it. Worked examples, why patterns ruin estimates, and a safe check.
- A strong Wi-Fi password that is still easy to typeWi-Fi passwords get typed on TVs, consoles and guests' phones. How to make one that is long and strong but painless to enter, and how to share it with a QR code.
- Title case rules: which words to capitalise in a headlineHow title case works, which small words stay lowercase, how AP, APA and Chicago styles differ, and when sentence case is the better choice.
- How to remove duplicate lines from a listClean duplicates out of email lists, product codes and copied data, keep the original order, catch near-duplicates, and find out which lines were repeated.
- How to sort a list properly — and why item10 comes before item2Sort lines alphabetically, numerically or by length, fix the item10-before-item2 problem with natural sorting, handle accents, and shuffle a list fairly.
- How to fix text copied from a PDF: broken lines, odd spaces and quotesText pasted from a PDF or web page arrives with a break after every line, strange spaces and curly quotes. Here is why, and how to clean it in seconds.
- How to make a Wi-Fi QR code so guests can connect in one scanCreate a QR code that connects phones to your Wi-Fi without typing the password, print it so it scans reliably, and fix the usual reasons it fails.
- How to make your resume ATS-friendly without keyword stuffingWhat applicant tracking systems actually do with your resume, the formatting that trips them up, and how to match a job advert honestly.
- How to turn a voice message into text — privatelyTranscribe WhatsApp and Telegram voice notes, phone recordings and short audio clips into text on your own device, and get the most accurate result.
- How long does it take to read or say 1,000 words?Reading and speaking times for any word count, how many words fit a five-minute speech, and how to hit a word limit for essays, posts and talks.
- Do QR codes expire? How to make one that never doesWhy some QR codes stop working and others last forever, how to make a free QR code with no expiry, and how to print one that always scans.
- UPC, EAN or Code 128: which barcode do you need?The main barcode types explained — 12-digit UPC-A, 13-digit EAN-13, EAN-8, ITF-14, Code 128 and Code 39 — and which one fits your products or labels.
- How to create a strong password you can actually useWhy length beats symbols, what makes passwords easy to crack, when to use a passphrase, and how to generate and check strong passwords safely.
- How many characters fit in a text message?The real SMS limits — 160 characters, or 70 with emoji — why long messages split into 153-character parts, and how to check before you send.
Work & documents
- Why an invoice’s tax total is off by a centTax rounded on each line rarely matches tax on the total. Why one-cent gaps appear between invoices, spreadsheets and accounts, and how to pick one rule.
- Why a CSV file opens in one column in Excel — and how to fix itEverything lands in column A when Excel expects a different separator. Why commas and semicolons clash between regions, and three ways to split it properly.
- How to stop Excel turning numbers into dates and dropping leading zerosExcel turns 1-2 into 1 Feb, 00042 into 42 and long IDs into 1.23E+15. Why it guesses, which changes cannot be undone, and how to import a CSV as text.
- How to convert minutes to decimal hours for timesheets7 hours 45 minutes is 7.75 hours, not 7.45. A minutes-to-decimal table, the formula, and how to avoid the most common timesheet and invoicing mistake.
- Invoice vs receipt vs quote vs estimate: which document whenA quote offers a price, an invoice asks for payment and a receipt proves it was paid. What each document is for, what goes on it, and where pro forma invoices fit.
- How to number invoices: formats that keep accountants happyInvoice numbers must be unique and usually sequential. Good formats, whether to restart each year, what to do with cancelled invoices, and mistakes to avoid.
- How to invoice a client in another currencyWhich currency to bill in, how to show it so nobody is confused, who pays bank and conversion fees, and what to record for tax when you invoice clients abroad.
- Resume vs CV: what is the difference?In the US a CV is a long academic record; in the UK it is a two-page job application. What each term means by country, how long each should be, and which to send.
- How to write a resume with no work experienceStudents, graduates and career changers can fill a page without job history. What to include instead, how to describe it, and a layout that works for a first resume.
- How to find the keywords in a job descriptionWhich words in a job advert matter for applicant tracking systems and recruiters, how to pick them out, and how to use them honestly in your resume and cover letter.
- How long should a cover letter be?Most cover letters work best at 250 to 400 words, under one page. What to put in each paragraph, when shorter or longer is right, and how to cut one down.
- How to name files so they sort in the right orderDates as YYYY-MM-DD, numbers with leading zeros and no final_FINAL_v2. A file naming scheme that sorts correctly on every computer and makes files easy to find.
- How to put a QR code on your business cardA vCard QR code lets people save your details to their phone in one scan. What to include, how big to print it, and why a smaller code scans more reliably.
- How to make an invoice that gets paid on timeWhat to put on an invoice, how to number it, clear payment terms, tax and discounts, and how to create a professional PDF invoice without an account.
- How to write a one-page resume that worksFit your experience onto one page without cramming: what to include, what to cut, how to write strong bullet points, and a layout tracking systems can read.
- How to format a LinkedIn post: bold text, spacing and the “see more” cutAdd bold and italic text to LinkedIn posts, keep line breaks intact, write an opening that survives the “see more” cut, and avoid the accessibility traps.
- How to pick a random winner fairly — and prove itRun a fair prize draw or giveaway: number the entries, draw without repeats, record the result so anyone can check it, and avoid the common mistakes.
Web & developer
- “Unexpected token < in JSON at position 0”: what it means and how to fix itThis error means your code expected JSON but got HTML, usually an error page or a login redirect. How to see what really came back and fix the cause.
- Why a site shows a certificate name error on www or without itA certificate covering example.com but not www.example.com (or the reverse) triggers a browser warning. How to confirm which names are covered and fix it.
- Why a link breaks when you paste it into an email, chat or documentPasted links fail when trailing punctuation, spaces, line wraps or unencoded characters change the address. How to spot the cause and share links that work.
- Why formatting or minifying HTML changed how the page looksWhitespace between inline elements renders as a space, so reformatting HTML can add gaps between buttons or images. Why, and how to make layout robust.
- Why your CSS isn’t being applied: a checklistA style that does nothing is usually overridden, mistyped, not loaded, cached or cut off by a missing brace. How to find which, using browser tools.
- Why an email bounces even though the address looks validA correctly formatted address can still bounce: the mailbox may not exist, be full, or reject your server. How to read the bounce and what to check.
- Why visits from your UTM links show up as direct or unassignedTagged links land in Direct or Unassigned when redirects strip tags, values are inconsistent, tags sit after # or analytics never loads. How to fix it.
- How to check an online tool really doesn’t upload your filesTwo quick tests show whether a web tool uploads your files: watch the browser's Network tab, and run the tool with Wi-Fi off. Works on any site.
- How to open a JSON file in ExcelTwo ways to get JSON data into a spreadsheet: Excel's Power Query import, or converting to CSV first. How nested data is flattened and how to avoid broken numbers.
- The year 2038 problem explainedOn 19 January 2038, 32-bit Unix time runs out and some systems will jump back to 1901. What exactly happens, what is affected, and how to check your own software.
- ISO 8601 date format explained (YYYY-MM-DD and beyond)2026-10-03T14:30:00Z decoded: the international date and time format, time zones and offsets, week numbers and durations, and why it is the safest format to use.
- How to embed an image in HTML or CSS with a Base64 data URIA data URI puts an image directly inside HTML, CSS or JSON. How to make one, the 33% size cost, where it helps, and why it often fails in emails.
- How to decode a JWT and read its claimsA JWT is three Base64URL parts separated by dots. How to read the header and payload, what the common claims mean, and why decoding is not the same as verifying.
- URL query parameters explained: what comes after the ?How to read the part of a web address after the question mark: keys and values, ampersands, fragments, encoding and tracking tags, and what not to put in a URL.
- UUID vs auto-increment ID: which primary key to useAuto-increment IDs are small and ordered; UUIDs are unique anywhere and hard to guess. The trade-offs for databases and APIs, and why UUIDv7 changes the answer.
- camelCase vs snake_case vs kebab-case: which naming style whereThe naming conventions used in JavaScript, Python, CSS, URLs, databases and environment variables, with examples, and how to convert between them quickly.
- How to fix an incomplete SSL certificate chainYour site works in a browser but apps, scripts and some phones report certificate errors. Usually the intermediate certificate is missing. How to check and fix it.
- SSL certificates are getting shorter lifetimes: what changes for youPublic TLS certificates are moving from about a year to 200 days, then 100, then 47 by 2029. The schedule, why it is happening, and how to make renewals automatic.
- How to check a domain's MX records (can it receive email?)MX records say which servers accept email for a domain. How to look them up, read priorities, spot null MX and missing records, and fix email after a move.
- Noindex vs disallow: how to keep a page out of GoogleDisallow stops crawling, noindex stops indexing, and using both together can backfire. Which to use for private pages, duplicates, PDFs and staging sites.
- Why your favicon is not showing in Google search resultsGoogle shows a generic globe instead of your icon. The size and format Google needs, where to declare it, how long it takes to update, and how to check each step.
- How long should a meta description be?Google cuts descriptions by pixel width, about 150 to 160 characters on desktop. How to write one that fits, why Google rewrites it, and what it does for clicks.
- What does lorem ipsum mean, and where does it come from?Lorem ipsum is scrambled Latin from a text by Cicero. What it says, why designers use it, its risks in real projects, and better placeholder choices.
- What is Base64, and when should you use it?How Base64 turns any data into plain text, why it makes things a third bigger, where it is used — data URIs, email, tokens — and why it is not encryption.
- URL encoding explained: what %20 means and when to encodeWhy web addresses contain %20 and %C3%A9, which characters must be encoded, the difference between encoding a whole URL and a single value, and %20 versus +.
- How to check when an SSL certificate expires — and why it mattersSee when a site's HTTPS certificate expires, spot chain problems browsers hide, and keep automatic renewal from failing silently as lifetimes get shorter.
- How to check an email address is valid before you sendCatch typos and badly formed email addresses, check that a domain can receive mail, clean a list in bulk, and understand what validation cannot prove.
- What is a UUID — and should you use version 4 or version 7?How UUIDs identify things without a central counter, how to read one, why collisions are not a practical worry, and which version to use for database keys.
- Structured data for beginners: FAQ and Product schemaWhat schema markup is, what FAQ and Product structured data can and cannot do for search results today, and how to add JSON-LD to a page correctly.
- UTM parameters explained: how to see which links bring you visitorsWhat utm_source, utm_medium and utm_campaign do, how to name them consistently, where the results appear, and the mistakes that corrupt your data.
- How to verify a file checksum (SHA-256) — and what it provesCheck that a download is exactly what its publisher released: find the checksum, compare it in your browser or from the command line, and understand its limits.
- How to fix invalid JSON: the common errors and what they meanTrailing commas, single quotes, comments, unescaped characters and the other mistakes that make JSON invalid — with examples and how to find the exact line.
- Unix timestamps explained: seconds, milliseconds and time zonesWhat a Unix timestamp is, how to tell seconds from milliseconds, why dates come out a day wrong, and the year 2038 problem — with examples you can check.
- How to fix link previews: Open Graph tags explainedWhy a shared link shows the wrong image, no image or an old title, which Open Graph tags fix it, the right image size, and how to make platforms refresh the preview.
- How to write a robots.txt file — with examplesWhat robots.txt can and cannot do, how the rules are matched, examples for common cases including AI crawlers, and the mistakes that hide a site from search.