How to compress a PDF online without losing quality

PDFBetter offers three levels. The lightest re-encodes images and keeps their resolution. The middle and strongest levels also lower image resolution, which is where the big savings come from and where fine print on a scan can start to soften. Match the level to what is in the file:

1. 1

   Open Compress PDF

   Drop your file onto the page. Files up to 10 MB work without an account or on a free account, and up to 50 MB on Starter. Unlock a password-protected PDF first.

2. 2

   Pick a level

   Use the table above. When in doubt, start with the middle level; you can run it again at another level.

3. 3

   Compare the sizes

   The result shows the original and the new size side by side, so you can see the savings before downloading.

4. 4

   Zoom in before you accept

   Open the preview and zoom into the smallest text, a signature and any photo you care about. If something looks soft, go one level lighter.

5. 5

   Download

   Download the smaller PDF. If it's still too big for your upload limit, see the next section.

Quality loss shows up in predictable places, so check those instead of scrolling through every page:

• The smallest text on a scanned page: footnotes, fine print, form labels. Zoom to 150%.
• Thin lines: handwritten signatures, table borders and stamps lose detail first.
• Photos with text in them: an ID card or a receipt, where the numbers must stay readable.
• Print, if it matters: if the file is going to a printer or a court, print one page at full size.

Typed text in a digital PDF never blurs, because it isn't a picture. If a page looks blurry at every level, it was a scan or an image to begin with. Running OCR PDF adds a searchable text layer to scans, though the page image itself stays as it is.

Compression has a floor: once images are lean, there is nothing left to squeeze. When a portal still rejects the file, change what is in it rather than how it is stored.

• Drop pages you don't need with Remove pages: blank scans, duplicate pages, cover sheets.
• Split it with Split PDF when the limit is per file, and upload the parts separately.
• Send a link instead with Share PDF when the limit is an email attachment cap.
• Rescan at a lower resolution if you control the scanner: 200–300 dpi is plenty for documents.

Sending by email specifically? Our guide to compressing a PDF for email covers attachment limits by provider.

Compression runs in PDFBetter's processing service, which receives the file, recompresses its images and returns the result. Files uploaded only to run a tool are deleted after 24 hours. If a file must not leave your computer, use the browser-only light mode: it restructures the PDF on your device without recompressing images, so the savings are smaller but nothing is uploaded.

Two things to do in the right order. Compress before you password-protect, because compression needs an unlocked file. And compress before anyone applies a certificate-based digital signature, since changing the file's bytes afterwards invalidates it.