Compress PDF
Make a PDF smaller without uploading it. Best for scanned PDFs: pages are re-saved as compressed pictures at the quality you choose.
Runs in your browser. Nothing you enter is uploaded.
What it does
Reduce the size of a PDF so that it fits an upload or email limit. There are two methods, and it is worth knowing which one you are using.
- Pages as compressed pictures shrinks scanned documents a great deal, but turns every page into a picture: text can no longer be selected or searched, and links and form fields are removed.
- Re-save only keeps everything as it is and packs the file’s internal structure more tightly. The saving is usually small.
How to use it
- Choose a PDF.
- For a scan or a PDF made of photos, use the picture method and adjust quality and resolution.
- For a PDF with real text that you need to keep selectable, use re-save only.
- Press Compress, compare the sizes, and open the result to check it before deleting your original.
Worked example
A phone-scanned document of several megabytes per page, re-saved at 100 dpi and quality 60, typically drops to a small fraction of its size while staying readable. A PDF exported from a word processor is already compact and may not get smaller at all; the tool tells you when that happens.
How it works
In the picture method, pdf.js draws each page at the chosen resolution, the page is saved as a JPG at the chosen quality, and pdf-lib builds a new PDF with one picture per page at the original page size. In re-save mode, pdf-lib writes the same content using compressed object streams. If the result is not smaller, the tool says so and you keep your original.
Questions
Is my file uploaded?
No. The file is opened by your browser on your own device and the result is made there. Nothing is sent to us or to anyone else.
Why can I no longer select text?
The picture method replaces each page with an image. Use re-save only if you need the text.
Why did my PDF not get smaller?
It was already efficient, usually because it contains text rather than scans. A lower quality or resolution in the picture method will shrink it further, at the cost of sharpness and selectable text.
Is there a page limit?
The picture method handles up to 150 pages. Split longer PDFs first.
Which settings should I use for a form upload?
Start with 100 dpi and quality 60. If the text is hard to read, raise the resolution to 150 dpi.