Compress PDF to 50 KB
Squeeze a one-page certificate, letter or declaration under 50 KB for a strict upload form. The PDF is compressed on this device and never uploaded.
- 100% free
- Runs in your browser
- No uploads
- Runs on your deviceEvery tool works directly in your browser. No files are uploaded.
- Your privacy mattersYour files never leave your device, so there's nothing for us to store.
- No limitsUse any tool as much as you need. No daily caps, no waiting.
- Completely freeNo signup and no trial to cancel. Ads keep the tools free.
How to compress a PDF to 50 KB
- Add the PDF. Drop it on the box or choose it. You can add several; each is compressed on its own.
- Leave the limit on 50 KB. Fit under a size is already selected. Type another number in Other size if your form differs.
- Compress, check and download. The bar shows the new size against the limit. Open the result and zoom in before uploading it.
When a form asks for 50 KB
50 KB is one of the smallest limits a form sets for a PDF. It usually comes with a one-page document in mind: a certificate, a declaration, a no-objection letter, uploaded next to a photo and signature with their own limits.
Whether it's realistic depends on how the PDF was made. A document typed in Word or downloaded from the issuing website is mostly text, and a few pages of it are often under 50 KB already. A scan is a picture of every page. In our tests a one-page A4 scan only got under 50 KB with the page image at 60 DPI, less than a third of the 200 DPI most scanners use. Headings and normal print stay readable; small print, stamps and signatures go soft.
What reaches 50 KB, and what doesn't
We ran sample A4 scans through this page in Chrome. Your files will differ, since busy pages and colour need more space, but the pattern holds: page count and colour decide whether 50 KB is realistic.
| Sample file | Before | After | How |
|---|---|---|---|
| 1-page greyscale scan, 200 DPI | 601 KB | 35 KB | Photos recompressed to 60 DPI |
| 1-page colour scan, 200 DPI | 675 KB | 37 KB | Photos recompressed to 60 DPI |
| 2-page colour scan, 200 DPI | 1.33 MB | 54 KB (didn't fit) | Pages re-rendered at 50 DPI |
| 3-page typed PDF, fonts embedded | 32 KB | 32 KB | Already under, original kept |
When nothing fits, the tool keeps the smallest version and says it couldn't reach the limit, rather than quietly handing you an unreadable file.
If it won't fit
Start from the digital original. If the certificate or letter exists as a PDF from the issuing site or from Word, upload that rather than a scan of a printout. It is text, not pictures, and much smaller.
One page per file. Two scanned pages didn't fit in our test. If the form only needs the page with the details, keep that one with Extract PDF pages.
Ask whether a JPG is allowed. Some forms take an image for the same field. A single page as a JPG can be brought under 50 KB with Compress image to 50 KB, and you can check its sharpness in the preview.
Other sizes
Frequently asked questions
Can a scanned PDF really be under 50 KB?
One page, yes, but only at a low resolution: about 60 DPI in our tests. Open the result and zoom in on the smallest print before you upload it. If it isn't readable, the form's reviewer won't be able to read it either.
My two-page scan won't go under 50 KB. What can I do?
Upload only the page that's needed, or split the document if the form has more than one upload field. Rescanning in greyscale with the margins cropped also helps. The tool stops at 50 DPI, because below that ordinary print is no longer legible.
Why does it say my original was kept?
Your PDF was already under 50 KB, or nothing the tool tried made it smaller. Typed PDFs often are. The file you download is then identical to the one you added.
Does it work on a phone?
Yes, in any recent mobile browser. Everything runs on the phone itself and nothing is uploaded, so a long scan can take a little longer than on a computer.