How to get a PDF under an upload limit (100 KB, 500 KB or 1 MB)

Application portals rarely say why, but most of them refuse anything over a fixed size: 100 KB for a certificate, 500 KB for a marksheet, 1 or 2 MB for a full document. The upload fails, the form times out, and the deadline is tonight. This guide is about hitting a specific number, not just “making it smaller”.

First, find out what is making the file big

A PDF typed in Word and exported directly is mostly text, and text is tiny: a ten-page report is often well under 500 KB. A PDF made from a scanner or phone camera is a stack of photographs, and a single photo of a page can be several megabytes on its own. Almost every oversized upload is the second kind.

If your document is a typed one that is still large, look for embedded photos or a logo saved at print resolution. Re-exporting from the original program with a “minimum size” or “web” setting often fixes it without touching the PDF.

Shrink it step by step

1. Open Compress PDF and add the file. It is processed in your browser and not uploaded anywhere.
2. Start with the Balanced level. It halves most scans while staying comfortably readable.
3. Compare the new size with the limit. If it is still over, run the original again on Strong.
4. Open the result and zoom to 100%. If you can still read the smallest print, such as a registration number, it is good enough to upload.

Compress the original each time rather than compressing an already compressed copy. Each pass loses a little detail, and two passes on Balanced usually look worse than one pass on Strong.

What compression changes

To get large savings, the compressor redraws every page as an image. That means the text in the compressed file can no longer be selected or searched. For scanned certificates that makes no difference, because they were images already. For a typed CV or cover letter it matters, because recruiters' systems read the text. Keep typed documents as text: re-export them instead of compressing them.

When it still will not fit

• Drop pages the portal did not ask for. Instruction pages, blank backs and duplicate copies all add size. Remove them with Delete PDF Pages.
• Upload in parts. If the form has separate slots, use Split PDF to send each document to its own slot.
• Rescan at a lower setting. For a 100 KB limit, a single page scanned in grayscale at 150 dpi is a realistic target; full-colour scans at 600 dpi are not.
• Crop the edges. A phone photo that shows the table around the paper wastes pixels on wood grain. Crop to the page before converting.

KB, MB and the limit itself

Some portals treat 1 MB as 1,000 KB and others as 1,024 KB, and some count the limit slightly differently from your computer. Aim about 5% under the stated limit so you are not caught by the difference. A file shown as 98 KB will pass a 100 KB limit everywhere; a file shown as 100 KB may not.

Mistakes that waste time

• Renaming the file or zipping it. Neither changes what the portal measures.
• Taking a screenshot of the PDF. It usually makes the file bigger and blurrier.
• Spaces and symbols in the file name. Some older portals reject them; use something like marksheet-2026.pdf.

For shrinking documents to send by email rather than to a fixed limit, see how to reduce PDF file size for email. To build the PDF from phone photos in the first place, see turning photos of documents into one PDF.