Online forms that ask for documents “under 100 KB” are common — and strict. This page opens the compressor already set to 100 KB, keeps text selectable whenever it can, and tells you plainly if your file cannot get that small.
Last updated: October 22, 2026
| Price | Free |
|---|---|
| Signup | None needed |
| Watermark | None |
| File limits | 50 MB per file, 200 MB per task; target preset to 100 KB (change it any time) |
| Where files are processed | On your device, in the browser — never uploaded |
| Works on phone | Yes — Android and iPhone browsers |
Government services, scholarship portals, exam registrations and admission systems often set tiny limits for each attachment: an ID page, a birth certificate, a mark sheet, a photo of a signature. The limit protects old systems from huge uploads, but it means a phone scan of a single page — often 1 to 3 MB — has to shrink by ten to thirty times.
The limit is usually per file, not per form. Read the instructions once: if each document can be uploaded separately, compress each one on its own; that makes 100 KB much easier to reach than squeezing several pages into one file.
It first tries Light compression, which shrinks the images inside the PDF and leaves text untouched, so a typed letter stays sharp and selectable. If that is not enough, it rebuilds each page as an image and searches for the highest resolution and quality that still fits, down to about 72 DPI.
The result always says which method was used and the exact size, using 1 KB = 1,000 bytes as upload pages count it. If a portal is stricter than that, set a custom target of 95 KB to leave a small margin.
Most 100 KB problems are scans. If you can scan again, a few settings make a big difference: scan or photograph at about 150 DPI rather than 300 or more, use grayscale for black-and-white documents, crop away the table or desk around the page, and keep the page flat and evenly lit so the background stays white instead of grey.
A clean, white background compresses far better than a shadowy one. If your scan has dark edges or a coloured tint, rescanning in better light usually beats any compression setting.
Some files simply cannot be readable at 100 KB — for example a ten-page scan, which would leave about 10 KB per page. When that happens the tool says so and offers the smallest version it could make. Then you have honest options:
Upload fewer pages. Remove pages the form does not ask for, or upload each page as a separate document if the form allows it. Rescan in grayscale at a lower resolution. Send an image instead: if the form accepts JPG, save the page as a JPG at Low quality — a single page is often smaller as an image. And if nothing works, contact the office: many accept documents by email or in person when a file cannot fit.
Open the compressed PDF and zoom in on the smallest text: names, dates, ID numbers, stamps and signatures must still be readable, or the document may be rejected later. If they are blurry, try a slightly larger custom target that still meets the limit, or rescan.
Give the file a clear name, such as surname-birth-certificate.pdf, so you can tell your uploads apart. No upload, no waiting — your file is processed on your device.
Many forms are filled in on a phone. The compressor works in the phone’s browser: choose the PDF from your files or downloads, and the 100 KB target is already set. Photos of documents? Make them into a PDF first, then compress.
Can I compress any PDF to under 100 KB?
No. A text PDF of a few pages usually fits easily, but long or detailed scans may not stay readable at 100 KB. The tool tells you when the target cannot be reached and offers the smallest version it could make.
Will my PDF still be readable at 100 KB?
A one-page document usually is. Always open the result and zoom in on names, numbers and signatures before you upload it.
Is 100 KB here the same as 100 KB on the upload form?
Yes. Sizes use 1 KB = 1,000 bytes, as upload forms count them. For a little extra margin, set a custom target such as 95 KB.
Does compressing to 100 KB keep text selectable?
Yes, whenever Light compression is enough. If pages have to become images to fit, the result says so and the text is no longer selectable.
Is my document uploaded to a server?
No. No upload, no waiting — your file is processed on your device.
Can I compress to a different size here?
Yes. The target is preset to 100 KB, but you can choose 200 KB, 500 KB, 1 MB, 2 MB or a custom size in the same box.