pdfpix

Compress PDF to 1 MB

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

1 MB here means 1,024 KB, which is 1,048,576 bytes. It is the most common attachment cap in the world, and it is reachable for most documents. The public bench ran a 1,000 KB target and met it on 5 of 10 cases. This page sets 1,024 KB, so it is marginally easier than that run.

How to compress a PDF to 1 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 1 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.

Why 1 MB is two different numbers

Mail servers and portals disagree about what a megabyte is. This tool uses the binary meaning, 1,024 KB, so the target is 1,048,576 bytes. A system that means 1,000,000 bytes is 48,576 bytes stricter, which is enough to bounce a file that fits here.

If an attachment is refused after it landed under 1 MB, that gap is the reason. Set the target to 950 KB on the compress tool and the file clears both readings. Mail also encodes attachments before sending, which adds roughly a third again, so a hard 1 MB mail limit really wants a file near 700 KB.

What a 1 MB budget buys

A twenty page text report fits comfortably. A ten page colour scan fits with visible but acceptable softening. A photo book does not. The engine spends the budget where the bytes are: it rebuilds the document structure, subsets the fonts, and only then reaches for the images.

That order matters. Two of the four methods never touch a pixel, so a file that reaches 1 MB through font subsetting or a structural rebuild looks identical to the original at any zoom level. Only the two image methods trade detail for bytes.

If 1 MB is not enough headroom

A cap of exactly 1 MB with no margin is a bad place to sit. Systems round, re-encode, and add wrappers. An 800 KB target gives you a quarter of a megabyte of slack for free, and on most documents the visible difference is nothing.

Going the other way, if the real cap is generous, a 2 MB target holds noticeably more image detail on scanned pages. The tool is the same and the target chip is the only thing that changes.

Questions

Does 1 MB mean 1,000 KB or 1,024 KB here?
1,024 KB, which is 1,048,576 bytes. The tool counts in binary units throughout. If the system you are uploading to counts in flat millions, it is stricter by 48,576 bytes, and a 950 KB target clears both readings.
Why did a 1 MB file get rejected by email?
Mail encodes attachments before it sends them, and the encoded form is roughly a third larger than the file on disk. A hard 1 MB mail limit is closer to 700 KB of actual PDF. Compress to 700 KB and the attachment goes through.
Will a 1 MB target blur my images?
Only if it has to. The engine tries the structural rebuild and the font subset first, and both leave every pixel untouched. Image quality is the last lever it pulls, and the tool reports which method won.
How long does compressing to 1 MB take?
Seconds for most files. On the public bench the median run took about 2.5 seconds start to finish, including reading the output back to check it, and the slowest case in the set took about 9 seconds.

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