How to compress a PDF
- Add one or more PDFs using the box above.
- Pick a strength. Light optimise rewrites the file structure and keeps everything sharp. Strong re-encodes the embedded images at lower quality for a much smaller file.
- Press Compress. Larger documents take longer because your own device is doing the work.
- The result shows the size before and after, so you can judge whether the trade was worth it before pressing Save.
About this tool
Compressing a PDF reduces its file size so it will fit an email attachment limit or an upload form that caps at 2 MB. This free PDF compressor shrinks documents in your browser, without sending them to a server.
Which setting to use depends on what is making the file big. If it is a text document that was simply saved inefficiently, light optimise often helps and costs nothing in quality. If the file is large because it contains photographs or scanned pages — which is usually the case — strong will make a far bigger difference, because it re-renders each page and re-encodes the images as JPEG.
Be aware of the trade-off: strong compression converts pages into images, so text in the output is no longer selectable or searchable. For a scan that was already an image, you lose nothing. For a text document you need to keep searchable, use light optimise and accept a smaller saving. Always keep your original.
Frequently asked questions
- How much smaller will my PDF get?
- It depends entirely on what is inside. Image-heavy and scanned documents often drop by 60–90% on strong. A text-only PDF that is already efficient may barely change, and the tool will tell you when that happens rather than pretending it worked.
- Why is my text no longer selectable?
- Strong mode renders each page to an image before re-encoding it, which removes the text layer. Use light optimise if you need the text to stay searchable.
- Is my document uploaded to compress it?
- No. Compression runs in your browser using your own processor. The document never leaves your device.
- Why is strong compression slow?
- Every page is rendered and re-encoded on your own machine. A long or high-resolution document genuinely takes time — there is no server farm doing it in the background.
- The file got bigger. Why?
- Some PDFs are already optimally packed, and re-saving adds a little overhead. The tool reports this instead of handing you a worse file.