pdfpix

Compress PDF to 10 MB

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

10 MB is 10,485,760 bytes. It is the cap on most mail providers and on many document portals, and it is where big scanned archives usually have to land. The bench did not measure a 10 MB target. The limit that bites first at this size is not compression, it is browser memory.

How to compress a PDF to 10 MB

  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 10 MB, 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.

The real ceiling is the tab, not the target

A compressor that runs in the browser has no server to hand the work to, so all of it happens in the tab. The source has to be held in memory, and so do the candidates the four methods build while they race. A source of a few hundred megabytes can run a tab out of room before any target is decided.

The large file page covers this directly. The short version is that a desktop browser with plenty of free memory handles far more than a phone, and splitting a huge document into parts is always safer than pushing one file through.

What lands at 10 MB

A two hundred page scanned archive at a readable quality. A photo heavy brochure. A technical manual with hundreds of diagrams. These are the documents where 10 MB is a genuine target rather than a formality.

The compress tool reports the size it reached and the method that won. On a scanned archive an image method almost always wins, and the quality it chose is worth reading, because it tells you how much headroom was left.

Before you compress a huge file

Remove what nobody will read. Duplex scanners leave blank versos, cover sheets get scanned by habit, and separator pages survive into the final file. On a two hundred page archive that can be forty pages of pure weight.

Then decide whether one file is the right shape at all. Ten files of twenty pages each open faster, download faster and survive a mail limit that one 10 MB file does not. A 5 MB target per part is a better outcome than one file that only just fits.

Questions

Why does my browser run out of memory on a large PDF?
Because the source and every candidate the methods build have to sit in memory at the same time. The tab has a fixed budget, and a few hundred megabytes of source plus working copies can exceed it. Splitting the file first avoids it entirely.
Is 10 MB a reasonable target for a scanned book?
For a couple of hundred pages, yes, at roughly 50 KB per page. Body text stays readable at that budget. Illustrations and small print do not fare as well, so check the worst page rather than the first one.
Does compressing to 10 MB take a long time?
Longer than a small file, because every page has to be processed and the output has to be read back and checked. On the published bench the slowest single case took about 9 seconds, and that corpus contained nothing near this size.
Can I compress a 10 MB PDF on a phone?
Sometimes, and it is the least reliable place to try. A phone browser has far less memory headroom than a desktop one, and a large file is exactly the case that exhausts it. Use a computer when the source is this big.

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