How to use Compress PDF
- Select or drop the PDF you want to compress.
- Choose a compression level. Recommended suits most files.
- Press Compress PDF and follow the progress bar.
- Compare the before and after sizes, then download the smaller file.
Supported formats and limitations
- Input
- One PDF
- Output
- Works on
- Any modern browser on Windows, macOS, Linux, Android and iOS. JavaScript must be enabled.
Important limitations
Savings depend on the file. PDFs that contain mostly text or that are already optimised may not get smaller; the tool tells you when that happens instead of giving you a larger file. CMYK and specially encoded images are kept unchanged.
Privacy and file processing
Processed in your browser. The file is never uploaded to our server.
About Compress PDF
Compress PDF shrinks large PDF files so they are easier to email, upload to government or job portals with size limits, or store. Most of the size in a typical PDF comes from photos and scanned pages, so that is where the tool works hardest.
At the Recommended and Extreme levels, embedded photos are downscaled and re-encoded as JPEG only when that actually makes them smaller. Every level also rewrites the file structure with qpdf to remove waste. Text and vector graphics are never turned into images, so documents stay sharp and searchable.
Features
- Three levels from lossless clean-up to maximum reduction
- Image downscaling and JPEG re-encoding that only keeps smaller results
- Object-stream and Flate optimisation with qpdf
- Shows original size, new size and percentage saved
- Never hands you a file larger than the original
Why use it
- Meet upload limits on portals and email
- Faster sharing on mobile data
- No upload: sensitive scans stay on your device
How it works
Photographic images (JPEG and 8-bit RGB or greyscale images) are decoded, downscaled to a maximum size for the chosen level and re-encoded as JPEG when that makes them smaller. qpdf then rewrites the file with compressed object streams and maximum Flate compression. Text and vector graphics are never rasterised.
Examples
Scanned application
Input: 8 scanned pages, 9.4 MB, Recommended
Result: Typically 1–2 MB, still easy to read.
Text-only report
Input: 1.1 MB report exported from Word, Low
Result: A modest saving from structure optimisation; text is unchanged.
Compress PDF: frequently asked questions
Which level should I pick?
Start with Recommended. Use Extreme when you must reach a strict size limit and can accept softer photos. Use Low when quality must not change at all.
Why did my file not get smaller?
It may contain mostly text, or its images may already be well compressed. The tool then keeps your original instead of producing a bigger file.
Can I compress to an exact size such as 100 KB?
Not exactly. Try Extreme; if the file is still too large, split it or reduce the number of scanned pages.