Compress a PDF to 100 KB
For exam boards, scholarship portals and older government forms. The compressor searches quality settings until your file fits under 100 KB — and it runs on your own device, so nothing is uploaded.
The compressor is on the front page. Set your target and go — nothing is uploaded.
Open the compressorWhat 100 KB actually means in practice
100 KB is an unforgiving limit. It dates from an era of much slower connections, and plenty of portals have never revisited it. For a document that is genuinely text — a typed letter, a filled form, a certificate — it is comfortably achievable. For a multi-page colour scan it is often physically impossible, and no tool on the internet will manage it while leaving the document readable.
If you cannot reach 100 KB, the honest fix is usually to reduce what you are compressing rather than compress harder. Scan in greyscale instead of colour, crop away the blank margins, or split a multi-page document and upload the pages separately if the form allows it.
How to do it
- Open the compressor on the front page and choose your PDF.
- Leave the method on Target size.
- Type 100 into the target box.
- Press Compress. The tool tries progressively lower resolutions and quality levels, measuring the real output each time.
- Download the result. It is the best-looking version that still fits under 100 KB.
If you cannot get there
When the tool reports a smallest achievable size above your target, it has genuinely exhausted its options. Things that actually help, in rough order of effectiveness:
- Scan in greyscale or black and white. Colour scans carry three channels of data for documents that are almost entirely black text on white paper. This alone often halves the size.
- Crop the margins. Phone photographs of documents usually include a desk, a hand, and a lot of empty space, all of which cost bytes.
- Reduce the page count. Many forms ask for specific pages, not the entire document.
- Rescan at a sensible resolution. 600 DPI is for archival reproduction. 150 DPI is fine for a form upload and a quarter of the size.
Common questions
Can any PDF be compressed to 100 KB?
No. Every document has a floor below which it cannot go while remaining readable. 100 KB is realistic for a one to three page text document, or a single scanned page. Beyond that, the honest answer is to reduce the page count or scan in greyscale rather than to compress harder.
Will the text still be selectable?
Not in Target Size mode. Guaranteeing a hard byte ceiling requires rasterising the pages into images, which flattens the text layer. Lossless mode preserves selectable text but cannot promise a specific output size.
Is my document uploaded to a server?
No. Compression runs entirely in your browser. The file never leaves your device, and the tool keeps working if you disconnect from the internet after the page has loaded.
Why does the form still reject my 100 KB file?
Check whether the limit is stated in KB or KiB, and whether the form also restricts page dimensions or requires a specific PDF version. Some portals also reject files whose name contains spaces or non-English characters.