Compress PDF

When do you need to compress a PDF?

The problem usually shows up at upload time: a portal rejects anything over 2 or 5 MB, or an email bounces because the attachment is too large. Most of the time the file was scanned or photographed with a phone, so every page is a large image. Compression shrinks those images until the system accepts your file.

The two compression types

The tool offers two options, each suited to a different case:

• Lossless: rewrites the file's internal structure more compactly without touching text or images. Text stays selectable and searchable. It helps with files exported by software that writes a messy structure, but it has little effect on scans and sometimes changes nothing.
• Strong: re-draws every page as a JPEG at the quality you choose, then builds a new PDF from those images. This is the option that actually shrinks scanned files. The trade-off is that text becomes part of the image, so it can no longer be selected or searched.

If either option produces a file that is not smaller than the original, the tool gives you the original back and tells you so. You never end up with a bigger file than you started with.

How to compress a PDF

1. 1
   Choose one PDF or drag it onto the box.
2. 2
   Start with "Lossless". If the result is still above the limit you need, switch to "Strong".
3. 3
   For strong compression, start at 60% quality. Lower it to 40% if you need a smaller file; raise it to 70% or more if small text becomes hard to read.
4. 4
   Click "Process now". The result message shows the size before and after and the percentage saved. Preview the file, then download it as compressed.pdf.

Tips for hitting a size limit

• Remove pages you don't need (a blank page, a duplicate scan) with Remove Pages first. Every deleted page reduces the size.
• Color scans where color doesn't matter (statements, ID copies) may get smaller after Grayscale PDF.
• If a single upload must stay under a limit but contains several documents, compress each one separately and then merge them, rather than compressing one huge file.

Limitations to keep in mind

• Strong compression is not suitable for a file whose text you'll need to copy later, or for an official contract that must stay searchable. Always keep the original.
• Password-protected files may not compress correctly. Remove the password first with Unlock PDF if you know it.
• Very large files are processed in your browser's memory and can be slow on older phones. A desktop computer is faster.

Where is the processing done?

Compression runs in your browser using pdf-lib and PDF.js, and your file is not sent to our servers. Once the page has loaded, you can disconnect from the internet and the tool keeps working.

Compress PDF: frequently asked questions