How to compress your PDF
- Pick a limit, or type the exact KB your form asks for.
- Choose colour, or black and white for text documents.
- Add your PDF. ReadyFile finds the sharpest result under the limit.
- Zoom in on the preview to check the text is readable, then save.
If your PDF is already under the limit, ReadyFile says so and gives it back unchanged.
Why forms limit PDF size
Application portals store thousands of documents, so they cap each upload, often at a few hundred KB. A phone scan or a PDF from a scanner app can easily be several MB, because it saves every page as a large, detailed photo.
How it works
ReadyFile draws each page, then saves it as an image at the sharpness that just fits your limit. The page count, order and page size stay the same.
- Colour saves each page as a photo-style image (JPG). Good for coloured documents, photos and stamps.
- Black and white saves each page as pure black and white, the way an office scanner does. Text stays crisp at a much smaller size.
Making a PDF from photos instead? Use JPG to PDF: add the photos, set the limit, and save one PDF.
Tips for small limits
- Black and white is the biggest saving for text. In our tests a 2-page scan needed 100 KB in colour to stay readable, and fitted 30 KB in black and white.
- Remove pages the form doesn’t need, such as blank backs of certificates.
- Scan flat and straight. Shadows and grey paper take up space in the file.
Questions
Is my PDF uploaded?
No. ReadyFile opens and compresses the PDF in your browser, on your own phone or computer. Certificates and ID documents never leave your device.
Why can't I select text in the compressed PDF?
To reach an exact KB limit, ReadyFile saves each page as an image. The pages look the same, but text can't be copied. Upload portals only check the file, so this doesn't affect your form. Keep your original if you need the text.
How small can it go?
It depends on the number of pages and how detailed they are. For text documents, choose black and white. It keeps text sharp at a fraction of the size, so even 30 KB is often possible for a couple of pages. If text would become hard to read, ReadyFile warns you.
Should I choose colour or black and white?
Black and white for text documents such as certificates, mark sheets and letters, unless your form asks for a colour scan. It saves each page as pure black and white, like an office scanner, so text stays crisp and the file is small. Photos, stamps and coloured logos turn solid black, so keep colour for those.
Is 1 KB 1,000 or 1,024 bytes?
Portals differ, so ReadyFile counts a maximum the strict way, 1 KB as 1,000 bytes. A file under 100 KB here passes a portal that counts either way.
My PDF has a password. Can I still compress it?
Yes. Enter the password when asked. It's only used to open the file on your device, and the new PDF has no password.
Last reviewed 22 Oct 2026 · How we check specs