pdfpix

Compress PDF to 500 KB

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

500 KB is 512,000 bytes and it is one of the four targets the public bench actually measured. The engine met it on 9 of 16 cases, 56.2%, the best reach of the four. It is the cap that job portals and grant systems reach for most, and it is loose enough to leave images readable.

How to compress a PDF to 500 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 500 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.

The measured reach at 500 KB

56.2% of cases met this target, which is the highest of the four the bench ran. Reach climbs with the cap for an obvious reason: the same amount of compression clears a looser bar. Below it sat 47.4% at 200 KB and 41.1% at 100 KB.

Across the whole run of 120 cases, 55 met their target and none came back larger than the source it started from. Every case that carried text kept 100% of its non-space characters, and no candidate was refused by the verification step.

What a 500 KB budget looks like on the page

On a five page scan that is 100 KB per page, which holds printed text cleanly and keeps a signature legible. On a twenty page report that is 25 KB per page, which is fine for text and charts and poor for photographs. The compress tool spends the budget where the weight is.

The method that wins tells you what happened. If the structural rebuild or the font subset won, nothing visible changed at all. If one of the image methods won, page images were re-encoded at a lower quality, and the quality it chose is reported.

Around the 500 KB mark

Portals that ask for 500 KB usually mean it strictly, so leave yourself room. A 400 KB target costs almost nothing extra in quality and clears both the binary and the decimal reading of the cap without argument.

If the cap has room in it, a 1 MB target roughly doubles the image budget. That is the difference between a scan you can read and one you can read comfortably.

Questions

How often does a 500 KB target succeed?
On the published run, 9 of 16 cases met it, which is 56.2% and the best of the four targets measured. The remainder came back smaller than the source with the reached size reported, rather than failing outright.
Is 500 KB small enough to email?
Yes, for every mail system in normal use. Mail encoding adds roughly a third, so a 500 KB PDF travels as about 670 KB, which is well inside even a conservative 1 MB attachment limit.
What does a 500 KB target do to a twenty page document?
It leaves about 25 KB per page. Text, line art and charts survive that comfortably. Photographs do not. If the document is mostly photographic, expect visible softening or pick a larger target.
Does the tool aim at 500 KB or under it?
Under it. The target is a ceiling, and the engine keeps the largest candidate that fits below it, so you get the best quality that still clears the cap rather than a file squeezed to the exact number.

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