pdfviz

Compress PDF
to 3 MB

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

3 MB is 3,145,728 bytes. It is the cap on a lot of application portals, and it is the practical size for emailing a document that has to stay readable. The published bench did not run a 3 MB target, so nothing here quotes a measured hit rate for it, but the targets either side give a clear picture of what to expect.

How to compress a PDF to 3 MB online

  1. Choose the PDF

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

  2. The target is already set

    This page opens with the target fixed at 3 MB, so there is nothing to type. Pick a different compression level if you want, or enter your own number in KB or MB for a different size.

  3. Press Compress

    Four methods race against each other: 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 whole process runs in your browser through WebAssembly, which means your file is never uploaded and no account is needed.

A colour scan against a text export at 3 MB

The same page count behaves completely differently at 3 MB depending on what the pages are. A forty page text export usually arrives under 3 MB before compression even starts. A forty page colour scan starts at twenty or thirty megabytes and has to give up most of it.

That split is the lesson the bench runs support: image quality is a dial with a long travel, while fonts and structure do not compress the same way. The document type matters more than the exact target number.

If your document is a text export, the lossless methods often reach 3 MB without touching a pixel. If it is a colour scan, the image method picks the quality that fits and tells you what it chose.

What a 3 MB budget buys per page

Twenty pages at 3 MB is 150 KB of image each, which is a good scan. Fifty pages is 60 KB each, which holds printed text and softens small type. A hundred pages is 30 KB each, which is where a scan stops being pleasant to read.

The compress tool reports the quality it settled on, so you can see where in that range you landed without opening every page. Check the page with the smallest type before you send the file, because that is the page where quality loss shows first.

For a text document, the per page budget is irrelevant because text weighs almost nothing. A hundred page text report fits easily under 3 MB through font subsetting alone, and the output renders as sharp as the original at any zoom.

Working around the 3 MB mail encoding overhead

If the cap is mail rather than a portal, remember the encoding overhead. Mail inflates attachments by roughly a third, so a hard 3 MB mail limit wants a PDF near 2.2 MB. A 2 MB target clears that without argument.

If the cap is generous, a 4 MB target buys a third more image detail for the same effort. The large file guide covers the case where the source is far bigger than any of these numbers. The tool is free, and it will reduce the file only as far as the target you name.

For a portal that counts in flat millions, a 3 MB target in binary is 3,145,728 bytes, which is 145 KB over the decimal limit. If you have been refused once, target 2.9 MB to clear both readings.

Real use cases for a 3 MB target

Application portals that cap uploads at 3 MB. Aiming slightly under the cap avoids the binary versus decimal counting problem that bounces files sitting right on the line.

Email attachments sent through systems with a 4 MB or 5 MB limit. A 3 MB PDF travels safely after mail encoding and clears the cap with room to spare.

Colour scans of twenty to fifty pages. At 60 to 150 KB per page, printed text stays readable and the file fits the common portal ceiling.

Questions about compressing a PDF to 3 MB

Is 3 MB enough for a fifty page scan?
It works out to about 60 KB per page, which holds printed body text and softens small print. Readable, not comfortable. If the pages carry footnotes or handwriting, a larger target or a split file is the better call.
How many bytes is a 3 MB limit?
3,145,728 bytes in binary units, which is what this tool uses. A portal counting in flat millions stops at 3,000,000, a gap of about 146 KB. Target 2.9 MB if you have already been refused once.
Why is my text document already under 3 MB?
Because text weighs very little. A page of text is a few kilobytes of drawing instructions plus a share of the embedded fonts. Documents only get big when they carry images, and a text export usually does not.
Does a 3 MB target touch the images at all?
Only if the two lossless methods fall short. The structural rebuild and the font subset run first and change nothing visible. The result names the winning method, so you know whether any pixel was re-encoded.
Will the text stay selectable after compression to 3 MB?
Yes. Every candidate is re-opened and its characters are read back and compared with the source. Anything below 98% retention is refused.
Can I compress a 3 MB PDF on my phone?
Yes. Files this size are well inside what a phone browser handles. The compression runs in the tab exactly as it does on a desktop, and your file never leaves the phone or desktop.

The other pdfviz tools

They all 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