pdfpix

Compress PDF to 300 KB

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

300 KB is 307,200 bytes. It is the number exam boards and visa portals reach for most often, usually for a scanned certificate or an identity page. The public bench did not run a 300 KB target, so this page quotes no measured hit rate for it, but it sits between two targets that were measured.

How to compress a PDF to 300 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 300 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.

Where a 300 KB cap comes from

Government and examination upload fields are written for one scanned page, not for a document. 300 KB is roughly what a decent A4 scan costs at a quality where the print stays sharp. That is why the cap keeps turning up on forms that expect a certificate or an identity page. A free browser compressor covers one page like that without an account and without an upload.

If your file is a single scanned page, 300 KB is comfortable. The compress tool will usually get there through image quality alone and leave you a page that still reads cleanly at full zoom.

What the measured targets say about this one

The bench ran 200 KB and 500 KB, either side of this. It met the 200 KB target on 18 of 38 cases and the 500 KB target on 9 of 16. Reach climbs as the cap loosens, so a 300 KB target sits between those two figures, though no run measured it directly.

Kind matters more than the exact number. Scans met their target on 16 of 18 cases across the whole run. Text documents met theirs on 10 of 50. If your 300 KB file is a scan, the odds are good. If it is a long text export, expect to remove pages.

Multi page scans at 300 KB

Divide before you start. 300 KB across four pages is 75 KB per page, which still holds printed text. Across twenty pages it is 15 KB per page, which does not. If the form takes one file per document, split the scan and upload the parts.

A 200 KB target and a 400 KB target are the two next stops. Try the tighter one first if the form has ever bounced a file on you; forms that count kilobytes in thousands are stricter than they look.

Questions

How many bytes is a 300 KB limit?
307,200 bytes when a kilobyte is 1,024 bytes, which is how this tool counts. A form that counts in flat thousands caps you at 300,000, which is 7,200 bytes tighter. Target 290 KB if you have been refused once already.
Is 300 KB enough for a scanned certificate?
For one page, comfortably. The print stays sharp and a stamp or seal stays legible. The trouble starts at four or five pages, where the per page budget falls to a level that softens small type.
Why do exam portals ask for 300 KB?
The field was sized for one scanned A4 page at a readable quality, which is roughly what 300 KB buys. The cap is about storage per applicant, not about the document, so it rarely changes even when the requested document gets longer.
Was a 300 KB target measured on the public bench?
No. The published run used 100 KB, 200 KB, 500 KB and 1,000 KB. The nearest measured points are 18 of 38 at 200 KB and 9 of 16 at 500 KB. Nothing here claims a hit rate for 300 KB itself.

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