How to Compress a PDF Under 100 KB Without Losing Readability
By Toolzy · · 2 min read
Government portals, exam forms and seller panels love a strict upload cap — often 100 KB or 200 KB. If your scanned document is a few megabytes, here is how to get it under the limit without turning the text into mush.
What actually makes a PDF large
Almost always, it's images. A scanned page, a photo dropped in at full camera resolution, or a deck full of screenshots — these dominate the file size. A PDF that is mostly selectable text is already small and compresses poorly, because there's little redundant data to remove.
So the biggest lever is resolution, not a vague "quality" slider.
The fastest path under a limit
- Open Compress PDF and drop your file in — nothing is uploaded.
- Start at 96 DPI and 70% quality. Check the before/after size shown for each file.
- Still over? Step the resolution down to 72 DPI. For a scanned form this is usually enough to cross under 100 KB while staying perfectly readable.
- Download the result.
Because everything runs on your device, you can iterate as many times as you like with no upload wait and no daily limit.
When compression won't (and shouldn't) help
If your PDF is a crisp, text-only report, rasterising it to hit a tiny target would trade selectable text for a blurry image and barely shrink it. In that case, the better fix is to export it correctly from the source application (e.g. "smallest file size" in your word processor) rather than compressing a finished PDF.
Bonus: convert images to PDF the smart way
Turning a folder of photos into a PDF? A photograph saved as JPG is far smaller than the same image as PNG. Use JPG to PDF for photos and keep PNG to PDF for crisp screenshots and line art.