Compress a PDF
Reduce the size of a PDF so it fits under email and upload limits. Choose how hard to compress and see exactly how much space you saved.
or drop a file here
One PDF, up to 250 MB.
Processed on your device. Nothing is uploaded.
How to compress a PDF
Add your PDF
Choose the file you need to shrink. Its current size is shown straight away.
Pick a level
Recommended suits most documents. Use Strong for bigger savings, or Maximum for scans.
Compress
Images are recompressed and the file structure is tidied, all inside your browser.
Compare and download
See the before and after sizes, then save the smaller file.
Key features
Image-aware compression
Photos and scanned pages are where the weight is. They are resized and re-encoded as JPEG at the level you choose; small images are left alone.
Structural clean-up
Unused objects are removed, uncompressed data is compressed, and the file is rewritten with compact object streams.
Never makes things worse
If a file is already efficient, you’ll get your original back with an explanation rather than a larger “compressed” copy.
Honest about trade-offs
Maximum compression converts pages to images. We tell you clearly that text stops being selectable before you choose it.
What to expect from PDF compression
How much a PDF shrinks depends on what is inside it. A scanned contract made of full-page photographs can often drop by 70–90%. A report exported from Word, made mostly of text and vector charts, may already be compact; compression might save only a few percent, and that is normal.
Fonts are another source of size. A document that embeds complete font families can be large even with no pictures. Compressing can’t safely remove fonts that the pages use, so for those files the gains are modest.
If the file is still too large
- Try the next level up. Strong usually looks fine on screen.
- Remove pages you don’t need with Delete Pages.
- Colour scans compress better in greyscale: run Greyscale PDF first.
- For upload portals with a per-file limit, split the document into parts.
For background on why PDFs get large, read our guide: Why are some PDFs so large?
Security and privacy
Compress PDF runs entirely in your browser. Your file is processed in this tab’s memory and never uploaded to PDF365 or anyone else. When you close the tab or press “Start over”, the data is discarded.
Compression only rewrites images and file structure. The text, links and form fields in your document are kept, except at the Maximum level, which deliberately flattens each page to a picture.
Read more in our privacy policy.
Questions about Compress PDF
Will compressing reduce the quality?
Images can lose some detail, more so at higher levels. Text and vector graphics are not affected at the Light, Recommended and Strong levels. Check the result before deleting your original.
Why did my file hardly shrink?
It was probably already well compressed, or most of its size comes from fonts rather than images. Text-heavy PDFs from office software are often close to their smallest size already.
Which level should I use for email?
Start with Recommended. Many email services cap attachments at 20–25 MB in total, so if you are attaching several files, Strong may be worth it.
Can I compress a password-protected PDF?
Not directly. Unlock it with Unlock PDF first, compress it, then add a password again with Protect PDF if you need to.
Does it work on scanned documents?
Yes, and they usually see the biggest savings. For scans you only need to read on screen, the Maximum level can make files dramatically smaller.