How to reduce PDF file size
A PDF that won't attach to an email or squeak under an upload limit is almost always bloated by images — high-resolution scans and photos that are stored at far more detail than the document needs. Compressing the PDF re-encodes those images at a sensible resolution and quality, which typically cuts the file to a fraction of its size while leaving the text perfectly sharp.
Below is the quickest way to do it, plus a short explanation of what's taking up the space so you can decide how hard to compress.
Step by step
- 1
Open the Compress PDF tool
Head to the Compress PDF tool and drop your file in, or click to browse for it.
- 2
Pick a compression level
Choose a balance between size and quality. A medium setting is usually indistinguishable from the original on screen; a stronger setting is best when you only need the file to be readable.
- 3
Compress and download
Run it and download the smaller PDF. Compare the new size against the original — if it's still too big, try a stronger level or remove pages you don't need first.
What makes a PDF large?
Text is tiny — a hundred pages of text is often under a megabyte. The weight comes from images: a single full-page scan at 300 DPI can be several megabytes on its own. Fonts embedded in full (rather than subset) and duplicated images add to it.
That's why compression focuses on images: it downsamples them to a resolution appropriate for the page and re-encodes them efficiently. If your PDF is mostly text and still large, the Sanitize and Optimize-for-Web tools can also trim metadata and restructure the file.
FAQ
Will compressing blur my text?
No. Text stays vector-sharp — compression only re-encodes images. Heavy settings can soften photos, so pick the lightest level that hits your target size.
What's the smallest I can make it?
It depends on the images. Try a stronger level, drop unneeded pages, or convert image-only scans to grayscale first if color isn't needed.
Is my file uploaded?
Compression runs on the server (it uses Ghostscript), over an encrypted connection, and the file is deleted within an hour. Most other tools here run fully in your browser.