pdfpix

Compress PDF to 20 KB

or drop one here
Compression level
Target size
Choose a PDF file first.

20 KB is 20,480 bytes, and almost nothing with a photograph on it reaches that. A short text document can. A scanned page, in any realistic quality, cannot. This page says so up front so you do not spend twenty minutes finding out, and shows what to aim for instead.

How to compress a PDF to 20 KB

  1. Choose the PDF

    Press Choose a PDF, or drop the file on the page. The file is read in this tab and is not sent anywhere.

  2. The target is already set

    This page opens at 20 KB, so there is nothing to type. Pick a different level, or enter your own smaller number in KB, if you want another size.

  3. Press Compress

    Four methods race: copy the pages into a fresh file, re-encode the placed images, cut each embedded font down to the glyphs the pages draw, and, only when no other method reached the target, redraw the pages as images with the text kept on top.

  4. Read the check, then download

    Every candidate is opened again and its characters are counted against the source. The page shows the size, the method that won and the characters kept before it offers the download.

The four methods are described in full, with the measurements behind them, in how it works.

Why 20 KB is out of reach for scans

20,480 bytes is smaller than a single low quality thumbnail. A scanned A4 page compressed to that size loses the letterforms, not just the sharpness. There is no setting and no tool that changes this, because the information is simply not representable in that many bytes.

The hardest target the public bench measured was 100 KB, five times this, and it met that one on 23 of 56 cases. Nothing in that run suggests 20 KB is reachable for a document with page images in it.

What does reach 20 KB

A one page text document with a single font, once the font is subset to the glyphs it draws. A signature or a logo on a white page. A generated receipt or ticket with no photograph. These are genuinely small documents, and the compress tool gets them there.

Font subsetting is what makes it possible. An embedded font ships with every glyph it was designed with, and a one page document draws a few dozen. Cutting the font down to what is used is often the difference between 200 KB and 20 KB on a text file.

What to aim for instead

Run it anyway and read the number it reached. That tells you the floor for your document. If the smallest proven file is 46 KB, then 46 KB is the answer, and the form is asking for something that does not exist.

A 50 KB target is the smallest that a simple scan sometimes reaches, and a 100 KB target is the smallest that is reasonable to plan around. If the form is fixed at 20 KB, it wants an image file, not a PDF, and it is worth reading the instructions again.

Questions

Can a scanned PDF be compressed to 20 KB?
Realistically, no. 20,480 bytes cannot hold a readable page image, and no tool changes that. A text only document can reach it once its fonts are subset, but a scan cannot.
What is the smallest file the tool produced for my document?
Whatever it reports after the run. When no method reaches the target, the engine ships the smallest candidate that passed verification and states the size. That number is the real floor for that document.
Should I lower the scan resolution to hit 20 KB?
You can, and it will still not be enough for a full page. It also destroys the print quality of the thing you are sending. If the requirement is genuinely 20 KB, the form almost certainly wants a small image rather than a document.
Why does font subsetting help so much at tiny sizes?
Because a font is a program carrying thousands of glyph outlines, and the page uses a few dozen. On a short text document the fonts can be most of the file, so cutting them to what is drawn removes most of the weight in one step.

The other pdfpix tools

All 30 of them run in a browser tab like this one. Each reads its own output back and checks it before offering the download, and none of them needs an account.

Where to go next