Compress a PDF to 100 KB — free, in your browser
Government portals, college admissions and job sites often set the same hard rule: your uploaded PDF must be under 100 KB. A scanned document is usually ten or twenty times that, so the form rejects it and the deadline does not move. The good news is that most of that weight is waste — oversized scans and uncompressed images — and it can be removed in under a minute, free, without uploading your document anywhere.
How to do it (about a minute)
Open the Compress PDF tool on Convert Files and drop your PDF in. Type 100 in the target KB box and press Convert. The tool re-compresses the images inside the PDF and strips the padding until the file fits at or under 100 KB, then hands it back to you as a download. Everything happens inside your browser — the PDF is never uploaded to a server, which matters when the document is a marksheet, an ID proof or a signed form.
Why PDFs get so big in the first place
Nine times out of ten, the weight is photographs and scans. A phone scanner app saves pages as full-resolution images; ten such pages can pass 5 MB without a single line of extra text. Text-only PDFs are the opposite: a typed ten-page document is often already under 100 KB, because text compresses extremely well. That is also why a scanned PDF shrinks dramatically while a typed one barely changes — there is simply more waste to remove.
Will 100 KB ruin the quality?
For form uploads, no. Portals store these files for records, not for printing, and examiners read them on screens. The tool lowers image resolution only as far as the target requires, so a document that starts at 300 KB usually stays perfectly readable at 100 KB. The honest limit: a very long scanned document — say 30 pages of photos — physically cannot reach 100 KB and stay readable. If that happens, split the PDF and upload it in the parts the form allows, or scan again at a lower DPI.
If the portal wants a different size
The same tool takes any target — 200 KB and 500 KB are one tap presets, and you can type any number the form asks for. For photographs and signatures the companion tool compresses images to exact sizes like 20 KB or 50 KB. One habit worth keeping: after compressing, open the result once and zoom in. Ten seconds of checking beats a rejected application.