pdfMB

Compress PDF

Make a PDF smaller, or fit it under the size limit a form asks for. Your file stays on this device.

How small should it be?
Fit under a size limitFor forms that say “max 200 KB”. You get the sharpest result that still fits.

Smaller files mean softer photos. Text, lines and tables always stay sharp and selectable.

  • No uploadYour file stays on this device.
  • Works offlineKeeps working once this page is open.
  • Free, no sign-upNo account and no daily limit.

What happens to your file

Everything below happens inside your browser, on your own device. The PDF is never uploaded, so nobody else, including us, can see it.

  1. Your browser reads the PDF into memory. Nothing is sent over the network. Once this page is open, it keeps working even if you go offline.
  2. pdfMB checks how large each photo actually appears on the page. A photo shown 5 cm wide does not need the detail of a poster, so it is resized to what the page needs: about 150 pixels per inch with “Balanced”.
  3. Photos are saved again with MozJPEG, an efficient JPEG encoder. Photos that are really black and white are stored in grayscale, which saves even more.
  4. Embedded fonts often contain thousands of letters the document never uses. pdfMB keeps only the letters that appear on your pages, and stores identical fonts once instead of many times.
  5. Leftovers that do not change how the pages look, such as page thumbnails and private data from editing programs, are removed.
  6. When you pick a size limit, pdfMB tries quality steps from best to lightest and keeps the best-looking result that fits.
  7. If the result is not smaller than your original, you get the original back unchanged.
In short
  1. Choose a PDF
  2. Pick a level or a size limit
  3. Press Compress
  4. Download

How to compress a PDF

  1. Choose your PDF, or drop it onto the box. pdfMB works on one file at a time.
  2. “Balanced” is already selected and suits most files. If your form or email has a limit such as 200 KB or 1 MB, pick it under “Fit under a size limit”.
  3. Press Compress. Most files take only seconds; large ones take longer, and you can cancel at any time.
  4. Download the result. The new file has “-pdfmb” added to its name, so your original is never overwritten.

When people use it

Job and school applications

Application portals often accept files only “under 200 KB” or “no larger than 1 MB”. Scanned certificates and transcripts are usually much bigger than that.

Government and visa forms

Online forms for visas, permits and taxes often have strict upload limits. Copies of ID cards and passports are private, so it is safer not to upload them to a compression website first.

Email attachments

Email services limit the size of attachments. Smaller files also send faster and are easier to open on a phone.

Sending in chat apps

Phone scanner apps often produce several megabytes per page. Compressed files are quicker to send and to download for the person receiving them.

Your own records

Receipts, payslips and contracts take up less space on your phone or in cloud storage.

What it can’t do

  • Text-only PDFs are usually small already. Text is kept as text, so there is often little to remove.
  • A very small limit for a long document may be impossible without turning pages into blurry pictures. pdfMB tells you instead of doing that.
  • Password-protected PDFs cannot be opened. Save a copy without the password first.
  • Black-and-white scans stored in fax-style formats (CCITT, JBIG2) and JPEG 2000 images are already compact, so they are left as they are.
  • Drawings made of lines and shapes (vector graphics) are kept exactly as they are.
  • Very large files (over about 100 MB) can be slow on older phones, because all the work happens on the device.

Questions about compressing PDFs

Will my PDF look worse?

Text, lines and shapes look exactly the same. Photos get lighter: with “Balanced” they stay sharp on screen and in normal printing. With a very small size limit, photos become softer, because that is the only way to fit.

What size should I pick?

Use the limit your form or website states. If it says “maximum 1 MB”, pick 1 MB rather than something smaller. The result will look better. If no limit is given, “Balanced” is a good choice.

Why did I get my original file back?

The PDF was already as small as pdfMB can make it without lowering quality, so a “compressed” copy would not have helped.

Can I still select and search the text?

Yes. pdfMB does not turn text into pictures. Text you could select and search before compressing can still be selected and searched afterwards.

Can I compress several PDFs at once?

Not yet. Compress them one after another. The page stays ready for the next file.