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Time Converter

Type a duration in any box to see it in every unit from nanoseconds to years at once. Up to a week the conversions are exact: a day is 86,400 seconds. Months and years are averages — a year is 365.2425 days and a month 30.44 — so for the time between two real dates, use the age calculator.

Runs entirely in your browser

Updated

How to use the Time Converter

  1. 1Type a value into any box — every other unit updates as you type.
  2. 2Use the swap button to flip the two headline units.
  3. 3Copy any result with the button beside it.
  4. 4Adjust the decimal places if you need more or less precision.

How it works

Everything up to a week is exact and unambiguous: a minute is 60 seconds, an hour 3,600, a day 86,400, a week 604,800.

Above a week it gets fuzzy, and it is worth being explicit about the choice made here. A year is taken as 365.2425 days — the Gregorian average, which accounts for the leap-year rules — and a month as one twelfth of that, about 30.44 days. That is why converting 1 month to days gives 30.44 rather than a whole number: there is no single correct answer, so the average is used. For real calendar arithmetic on specific dates, use the age calculator instead.

Conversion works by taking your value to a single base unit and then out again, so every pair of units is consistent with every other. Values are calculated at full double precision and only rounded for display, which means round-tripping a number through two conversions returns what you started with.

The formula

value in target = (value × seconds per source unit) ÷ seconds per target unit
second
the base unit every duration is defined against
year
taken as 365.2425 days, the Gregorian mean
month
taken as one twelfth of a mean year

Common time conversions

Months and years have no fixed length, so the converter uses the average Gregorian year of 365.2425 days.

FromEquals
1 minute60 seconds
1 hour60 minutes
1 hour3,600 seconds
1 day24 hours
1 day1,440 minutes
1 day86,400 seconds
1 week168 hours
1 week10,080 minutes
90 minutes1.5 hours
45 minutes0.75 hours
1,000 minutes16.6667 hours
10,000 seconds2.7778 hours
1 year (average)365.2425 days
1 year (average)8,765.82 hours

Tips and common mistakes

  • Units up to a week are exact; months and years are averages.
  • For the time between two real dates, use the Age Calculator, which counts calendar days.
  • On timesheets, remember decimal hours are not minutes: 7.5 hours is 7 hours 30 minutes.
  • Use seconds or milliseconds when working with computer timestamps.

Frequently asked questions

How many seconds are in a day?
86,400 — that is 24 hours × 60 minutes × 60 seconds.
How many minutes are in a day, and hours in a year?
A day has 1,440 minutes. A 365-day year has 8,760 hours; a leap year has 8,784. Averaged over the Gregorian calendar a year is 8,765.82 hours, or 31,556,952 seconds, which is the figure this converter uses.
Why is a month 30.44 days here?
Because calendar months are 28 to 31 days long, so any single conversion has to use an average. 30.44 days is one twelfth of a mean Gregorian year.
How do I work out the time between two dates?
Use the age calculator, which counts real calendar days including leap years, rather than averaging.
How accurate are these conversions?
Sub-day units are exact. Months and years are averages, since calendar months vary in length. All arithmetic is done at full precision and rounded only when displayed, so results are exact to the digits shown.
How do I convert decimal hours to hours and minutes?
Multiply the decimal part by 60. 7.75 hours is 7 hours and 0.75 × 60 = 45 minutes.
How many weeks are in a year?
About 52.18 on average: 365.2425 days divided by 7. A common year is 52 weeks and one day.
How many seconds are in a year?
31,536,000 in a 365-day year and 31,622,400 in a leap year. The Gregorian average used here is 31,556,952.
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