How to compress a PDF to under 100 KB
Open Compress, choose To a size, pick 100 KB and press Compress it. The file is made smaller in your browser, so it never leaves your phone or computer.
CompressFree. Nothing is uploaded.
How to do it
- Open the Compress tool and add your PDF.
- Choose To a size under How to squeeze.
- Pick 100 KB.
- Press Compress it and read the line under the result, which gives the new size.
- Save the file, or tap Share to send it to another app.
Why portals ask for 100 KB
Exam, job and scholarship portals keep each upload small so that lakhs of applications fit on their servers and open quickly for the people checking them. A photo of one page straight from a phone camera can be 2 or 3 MB, so a scanned certificate is usually far over the limit before you start.
What gets smaller, and what does not
Compress shrinks the photos inside the PDF, trying the gentlest setting first and stopping at the first one that fits under 100 KB. Typed text and lines are never touched, so they stay crisp. The result says how sharp the photos still are.
If photos alone cannot get the file under 100 KB, the result says so. Tick Let pages become pictures and run it again: each page is redrawn as one picture, as sharp as the limit allows. It looks the same, but the words can no longer be selected, which an upload portal does not care about.
When 100 KB is still too small
A long document may not fit in 100 KB and stay readable. Upload only the pages the portal asks for: Extract pages makes a file with just those. If you are photographing a certificate, Scan in Black and white gives a far smaller file to begin with than a colour photo.
We count 1 KB as 1,000 bytes. A file made under 100 KB here is also under 100 KB on a portal that counts 1 KB as 1,024 bytes.
Common mistakes
The most common one is compressing a file that was already compressed, again and again. Each round softens the photos a little more while the size barely moves. Always start from the original: Compress never changes the file you picked, so it is still there to go back to.
Another is photographing a certificate in colour under a yellow bulb. The colour cast, the shadow and the table around the page all take up room that sharp text could have used. Re-take it in daylight, or use Scan in Black and white, before you compress.
Questions people ask
Will my document still be readable?
For most certificates and forms, yes. Compress picks the gentlest setting that fits. If 100 KB is too small for the file to stay readable, it tells you so, and with Let pages become pictures ticked it gives you the smallest version that still reads.
Is my file uploaded anywhere?
No. The work happens in your browser, on your device. Nothing is sent to us or anyone else, and the tool keeps working with the internet switched off.
Can I compress several PDFs at once?
Yes. Add them all and each comes back under 100 KB. Save all saves them together, as a folder or one ZIP.
The portal wants a JPG, not a PDF. Will this help?
Not directly; Compress makes PDFs smaller. To turn a page into a picture, use PDF to images with JPEG at Screen sharpness, which gives the smallest image.
The portal says my file is still too big. Why?
Check that you chose the new file, not the original: the new one’s name ends with (under 100 KB). If the portal still refuses it, run it again with Other and a slightly lower size, such as 90, in case the portal counts differently from what it says.
Can I do this on my phone?
Yes. It works in the phone’s browser. A long scan takes a little longer on a phone than on a computer, and a line shows what it is doing.
Your file stays on your device. Foolscap does the work inside your browser, so nothing is uploaded and there is nothing for anyone to keep. How you can check