How to compress a PDF to 100 KB
- Tap Choose your PDF and pick the document the portal turned down.
- Leave the target at 100 KB and tap Compress to 100 KB.
- Watch the pages go past — a long scan takes longer than a single sheet.
- Check the finished size, then save it.
Why the same 100 KB target behaves so differently
The number is a limit on the whole document, so it is divided between however many pages you brought. Two scanned pages get about fifty kilobytes each and come out looking fine. Fifteen pages get under seven kilobytes each, which is not enough to keep small print legible, and the tool will land above the cap and say so rather than pretend otherwise.
What is on the pages matters as much as how many there are. A photocopy of typed text compresses much further than a colour photograph of the same sheet, because there are only two tones in it. Where you can choose how a document is scanned, black and white at 200 to 300 DPI is the setting that makes a hundred kilobytes comfortable.
It weighs the real file, not an estimate
Guessing the size of a PDF from the size of its parts is close but never exact, and "close" is what produces a 104 KB file against a 100 KB cap. Here the last step writes the document out for real and measures it. If that comes out over, it drops a rung and writes it again, so what you are handed is a file somebody has actually weighed.
The aim sits about ten per cent under the number in the URL, and that is deliberate too. Some portals count a kilobyte as 1,024 bytes and some as 1,000, so a file at 99,900 bytes passes one and fails the other. Landing near 90,000 clears both, and the page prints the exact figure it reached.