How to Reduce a PDF to 100 KB
By PDFOak · Published September 9, 2026 · Updated October 1, 2026
A 100 KB limit is realistic only for a short, simple document. Keep the original and judge the result by readability, not just the final number.
The figures below are arithmetic, not a test of a real file, so read them as a rough budget.
The budget for a five-page scan
The compressor sets aside about 3 KB for file structure plus about 600 bytes per page. For five pages that is roughly 6 KB, which leaves around 94 KB of image data, or about 19 KB per page. Ten pages would leave about 9 KB each.
Clean black-and-white text fits a budget like that far better than a colour photograph or a shadowed phone scan.
Cut before you squeeze
Every page you drop gives the others a bigger share. Use Extract Pages to keep just the pages you need. Delete Pages can leave the removed pages’ images inside the file, so it does not reliably shrink it.
Improve the source
Crop empty scanner borders, rescan in grayscale when colour carries no meaning, and avoid camera shadows. A clean source gives the compressor fewer noisy pixels to preserve.
A born-digital one-page form may already be under 100 KB. If it is, leave it alone.
Check the result
Open the download and read names, dates, numbers and stamps at 100% zoom. If you cannot, the fix is fewer pages, a cleaner scan, or asking whether the recipient accepts a larger file. Do not submit unreadable evidence.
The steps, in order
- Decide which pages the recipient actually needs.
- Extract those pages into a new PDF.
- Unlock the file first if it is password protected.
- Open the 100 KB preset, and accept a text-loss warning only if text is not required.
- Download the result and read every name, number and stamp.
Frequently asked questions
What if the PDF cannot reach 100 KB?
Reduce the page count, start from a cleaner scan, or confirm whether the receiving system accepts a larger file. If even the lowest setting is too large, the tool says so instead of returning an oversized file.