Compress PDF to 100 KB

100 KB is a tight limit, so it helps to know what you are aiming for before you start.

• A typed document of one to five pages (exported from Word or Google Docs) is often already under 100 KB. If yours is bigger, it usually carries embedded fonts or a large logo.
• One scanned A4 page fits comfortably at around 100 dpi in color, and with room to spare in grayscale.
• Two or three scanned pages usually need grayscale and 72 dpi or less to fit.
• A ten-page scan almost never fits in 100 KB with readable text. In that case, send only the pages the form actually asks for.

The file size of a scan depends mostly on the number of pixels, so halving the resolution roughly quarters the size. Text on a page scanned at 72 dpi is still readable on screen, but small print and stamps get soft.

You don't have to guess a setting. In target mode the tool first tries its strongest level. If even that is too big, it tells you right away instead of wasting time. If it fits, the tool searches upward through the levels (from 50 dpi up to 200 dpi) and keeps the best-looking version that is still under 100 KB. Between two neighbouring levels it makes one more attempt, so the result lands as close to the limit as possible without going over.

In Recommended mode only the images inside the PDF are made smaller. Typed text, lines and tables stay sharp and searchable at any zoom. In Strong mode every page becomes a single image. That is the only way to shrink a PDF whose size comes from fonts or complex vector drawings, but the text can no longer be selected or searched.

If your PDF is already under 100 KB, it is left exactly as it is, and the tool says so.

Sometimes even the strongest level produces a file that is too big. The tool then gives you the smallest version it could make and marks it clearly, so you never upload a file that will be rejected. You have a few options:

1. Switch to Strong mode and turn on grayscale. For black-and-white paperwork (certificates, IDs, forms) a grayscale page is often a third of the color size, and nothing important is lost.
2. Remove pages you don't need. A blank back side or a cover page costs as much as a page with text. Use the delete pages tool, then compress again.
3. Split the document. If the portal accepts several uploads, split the PDF into parts that each fit.
4. Rescan at a lower resolution. A phone scanner app set to 150 dpi gives a better starting point than a 600 dpi office scan.

Most documents that have to be under 100 KB are scans: degree certificates, ID cards, payslips, signed forms. A few habits make a big difference:

• Scan in grayscale from the start if the document has no meaningful color. A color scan of white paper still stores three color channels of slightly yellowish noise.
• Crop the edges. Dark borders around a scanned page waste space and look untidy. Crop before converting to PDF.
• Use good light if you photograph the page with your phone. Shadows and grain are hard to compress, while even, bright paper compresses well.
• Check readability at 100% zoom after compressing. Small print, stamps and signatures are the first things to blur. If they are hard to read, send fewer pages at a higher quality instead of more pages at a lower one.

The tool never changes the order or content of your pages; it only changes how the images are stored.

The compression runs entirely in your browser using JavaScript and WebAssembly. The PDF is read from your disk, processed in memory and saved back to your downloads folder. Nothing is uploaded to a server, which matters when the document is an ID card, a bank statement or a medical record. Once the page has loaded, the tool keeps working even if your connection drops.