Compress PDF to 300 KB
Recommended compression is pre-selected to hit this limit.
The 10-second test: switch off your Wi-Fi (or turn on airplane mode) and use this tool anyway. It keeps working — because there is no server doing the work.
The technical check: open your browser's developer tools, go to the Network tab, and run the tool. Your file is never sent anywhere.
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How to compress a PDF to 300 KB
300 KB is a forgiving target. Recommended compression is pre-selected because at this size you do not need to punish the images — most documents land under the line with quality that still looks good on screen and prints acceptably.
Why you might prefer 300 KB over a tighter limit
If the form allows it, aim here rather than at 100 KB. The difference in what a human sees is significant: at 300 KB a scanned signature stays crisp and small print stays sharp, whereas heavy compression can soften both. Only go smaller when the upload form forces you to.
Other targets
Why file size is almost always images
Text costs very little space — a 200-page text document is often under 1 MB. A single high-resolution scan of one page can exceed 5 MB. Compression works on the images and leaves the text alone, which is why scans shrink enormously and text documents barely move.
If Recommended is not enough
Switch to Extreme on the options panel, remove blank scanner pages with Remove Pages, or split the document with Split PDF. If the form allows more headroom, 500 KB gives a noticeably better-looking result.
Need a different size limit?
Frequently asked questions
Is 300 KB small enough to email?
Comfortably. Mail providers start objecting in the tens of megabytes, so a 300 KB attachment is never a problem.
Should I use Recommended or Extreme for 300 KB?
Start with Recommended, which is pre-selected. Only switch to Extreme if the result lands above your limit.