Compress PDF to 100 KB

A 100 KB limit turns up on school admission and government application forms, and a color scan of one page can easily be over 1 MB. Our 300 DPI sample page was 1.90 MB. This tool is already set to 100 KB. It tries one setting after another and keeps the sharpest version that fits.

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PDF · 30 MB per file · 100 MB total

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Good to know before you begin

Reaching a small size usually means saving pages as pictures, which removes searchable text, links and form fields. The tool aims at or under the target, counting 1 KB as 1,000 bytes. If it can’t get there, you get the smallest version with a note saying so.

How to compress a PDF to 100 KB

Select Choose a PDF, or drag your file onto the box.
Check that Target size says 100 KB. This page sets it for you.
Select Compress PDF →. The tool tries Optimize first, then picture versions of your pages at lower and lower resolution.
Read the line under Your file is ready. It tells you whether the file got under 100 KB and at about what resolution.
Select Download result ↓, then open the file and zoom in on the smallest print before you upload it.

What fits in 100 KB

100 KB is a tight budget for a scan. We tested with sample scans we made ourselves: letter-size pages scanned at 300 DPI in color, mostly printed text.

A one-page scan of 1.90 MB came out at 88.9 KB, with the page saved at about 100 DPI. The text was easy to read.
A three-page scan of 5.87 MB came out at 78.9 KB, but only at about 56 DPI. The text was still readable, but soft, and the tool warned us to check it.
A six-page scan of 15.28 MB, full of photo-like detail, could not get under 100 KB at all. The smallest version was 135.2 KB at about 40 DPI, and the tool said so rather than giving us a file that would be rejected.

So one page per file works well at 100 KB. Three pages or more usually means a blurry result.

Example: school admission uploads

Delhi’s EWS/DG/CWSN school admission portal asks for clear, readable scans of documents such as the birth certificate and income certificate as PDFs of no more than 100 KB each (portal instructions, checked Oct 30, 2026). Each document gets its own file, which suits this page. Scan each certificate on its own, then bring each file under 100 KB separately.

Some portals also set a minimum. UPSC’s online application asks for certificate PDFs between 50 KB and 300 KB, with set file names (UPSC upload instructions, checked Oct 30, 2026). If your portal has a floor like that, check the size of your result before you upload. When the limit is 300 KB, you don’t need to squeeze to 100 KB: change Target size to Custom and type 300, and the page will be noticeably sharper.

If it won’t get under 100 KB

Remove pages the form didn’t ask for, such as blank backs or instruction sheets, with Organize PDF or Split PDF, then compress again.
Rescan in grayscale or black and white if your scanner app offers it, and crop to the edges of the paper so the file isn’t spending bytes on the table around it.
Ask whether the form accepts more than one file. If it does, split the document and compress each part.
If the tool reports a password-protected file, it can’t open it. Use a copy without a password.

What you give up

To reach 100 KB the tool almost always saves each page as a JPEG picture. The result looks like your document, but you can’t select or search the text, and links and form fields are gone. Keep your original. If the portal wants a fillable form, compressing this hard is the wrong fix.

On a computer or phone

On Windows and Mac, the result goes wherever your browser saves downloads. The tool also works in mobile browsers, but large scans take longer on a phone than on a laptop, and very long files can run out of memory. On iPhone, Safari saves the result to the Downloads folder in the Files app (Apple’s instructions). On Android, Chrome saves it to Downloads (Google’s instructions). On a phone, a single page is the easiest case and usually finishes in a few seconds.

Questions

Is 100 KB counted as 100,000 or 102,400 bytes?

Portals differ, and few say. The tool aims at or under 100,000 bytes, which fits either way. Your phone or computer may show the same file as about 97 KB.

Why is my file 60 KB when I asked for 100 KB?

The tool steps through a fixed set of resolution and quality settings. If the next sharper setting went over 100 KB, you get the one below it, which can be well under the limit.

Is my file uploaded to PDFReadyGo?

No. The PDF is read and compressed in your browser. The limits are 30 MB per file and 100 pages for picture-based compression.

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