Compress a PDF
Make a PDF small enough to attach. Pick a quality level and see the result before you save.
Compress PDF
Never uploadedYour file is processed in this tab and never sent anywhere.
How to compress pdf
- Drop the PDF. The current file size shows immediately.
- Pick a level. Light, balanced, or strong. Each shows the resulting size before you commit.
- Save the smaller file. Compare the numbers, then download the version you want.
About compress pdf
Almost every PDF that is too large is too large for one reason: it contains photographs of paper. A scanner producing 300 DPI colour images of twenty pages will make a 40 MB file out of a document that is, in information terms, a few kilobytes of text. Compression is really a question about those images — how much resolution and colour fidelity you are willing to trade for a file that fits through an email gateway.
The tool renders each page with PDF.js at a resolution matched to your chosen level, re-encodes it as a JPEG at a matched quality, and rebuilds the document from those images with pdf-lib. It is a lossy process and it is honest about that. The pages become pictures. Text that was selectable stops being selectable, because it stops being text. In exchange you typically get a file a fraction of its original size, and for a scanned document being sent as an attachment that is usually the right trade.
What to pick depends on what the file is for. Light keeps enough resolution for the document to be printed and read comfortably, and often halves the size. Balanced targets on-screen reading and email attachment, which is what most people actually need. Strong produces the smallest file and is appropriate when the recipient will glance at it on a phone and never print it. The tool shows the resulting size for each so you can decide against a number rather than a label.
Where this approach does not help: a PDF that is large because it contains a great deal of genuine text and vector content, which is already compact and will not shrink usefully. A 200-page text report at 4 MB is already efficient. If the size is coming from text, rasterising it makes the file larger, not smaller, and destroys the text layer for nothing. The tool tells you when the output would be bigger than the input rather than letting you save a worse file. If you need the text layer preserved, do not compress — split the document and send it in parts instead.
Quality levels
| Level | Render at | Typical reduction | Good for |
|---|---|---|---|
| Light | 150 DPI, quality 0.85 | 30–55% | Documents that will be printed |
| Balanced | 110 DPI, quality 0.72 | 55–80% | Email attachments and screen reading |
| Strong | 80 DPI, quality 0.55 | 75–92% | Phone viewing, size limits under 5 MB |
| Restructure only | No re-render | 0–12% | Text PDFs where the text layer must survive |
Compress PDF FAQ
How do I get a PDF under 25 MB for email?
Start with balanced and check the resulting size. If it is still over, move to strong. Most scanned documents drop below 25 MB at balanced. Gmail's limit is 25 MB and Outlook's is commonly 20 MB, so aim under 20 to be safe.
Will compressing make my text unselectable?
Yes, at any level that re-renders pages. Compression turns pages into images, and images have no text layer. Use restructure-only mode if the text layer must survive, though it saves far less.
Why did my file barely get smaller?
Because it was mostly text and vectors rather than scanned images, and those are already compact. There is little to squeeze out. The tool will tell you when this is the case.
Which level should I use?
Balanced for anything going by email. Light if it will be printed. Strong when there is a hard size limit and the document only needs to be readable on screen.
Is the file uploaded to be compressed?
No. Rendering uses PDF.js and rebuilding uses pdf-lib, both in this browser tab. Nothing is transmitted.
Can I compress a scanned document without losing readability?
Usually yes at light or balanced. Scanned text stays legible well below the resolution most scanners default to, because 300 DPI is far more than a screen needs.