pdfpix

Compress PDF to 5 MB

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

5 MB is 5,242,880 bytes, and it is the attachment ceiling on most corporate mail systems. It is a loose cap for a document and a tight one for a photo album. The bench did not run a 5 MB target, so no hit rate here is measured, but most documents that arrive at this page will clear it.

How to compress a PDF to 5 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 5 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 mail systems that stop at 5 MB

Plenty of corporate mail gateways cap attachments around 5 MB, and some smaller providers still sit at 10. The number to watch is not the file on disk. Mail encodes attachments before sending, and the encoded form is roughly a third larger, so a 5 MB limit really wants a PDF near 3.7 MB.

A 3 MB target clears that with room to spare and rarely costs anything you can see. If the recipient bounced your last attachment without explanation, the encoding overhead is the most likely reason.

What 5 MB holds

A hundred page text report fits easily. A thirty page colour scan fits at a quality that still reads well. A folder of phone photographs turned into a PDF usually does not, because a single modern phone photo can be 4 MB before anything else is counted.

The compress tool tries the two lossless methods before it touches image quality, so a document that reaches 5 MB through a structural rebuild or a font subset is byte for byte as sharp as the original.

When the source is much bigger

Very large sources bring their own limit, and it is the browser tab rather than the algorithm. A file of a few hundred megabytes has to be held in memory alongside its candidates. The large file page covers where that ceiling sits and what to do about it.

For an archive scan, splitting by chapter and compressing each part beats compressing the whole. Every part gets the full budget, and the pages stay readable instead of being flattened to make room for pages nobody is going to open.

Questions

Is a 5 MB PDF small enough to email?
Usually, but not always. Mail encoding adds about a third, so a 5 MB file travels as roughly 6.7 MB. Against a hard 5 MB gateway limit that bounces. Compress to about 3.7 MB and it goes through.
How many bytes is 5 MB?
5,242,880 bytes in binary units, which is what the tool uses. A system counting in flat millions stops at 5,000,000. The gap is 242,880 bytes, enough to matter when you are sitting right on the line.
Does a 5 MB target change image quality?
Often not at all. Two of the four methods leave every pixel untouched, and on a document that started under about 8 MB they frequently reach the target on their own. The result names the method that won.
My PDF is 200 MB. Can it reach 5 MB?
Sometimes, and the more useful question is whether the browser can hold it. Very large sources run into a memory ceiling before they run into an algorithmic one. Splitting the document first is the reliable path.

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