Compress PDF
Shrink PDF file size so it fits email and upload limits.
Loading tool…
Reduce the size of PDF files so they meet email attachment and website upload limits. Drop in a PDF, choose a compression level, and the tool rebuilds the document with optimised images to bring the size down. Everything runs in your browser using pdf-lib and pdfjs, which keeps your documents private and avoids waiting on a server.
Why PDF files get so large
Most oversized PDFs are heavy because of images. A document that is mostly text is usually small, but the moment you add high-resolution photos, scanned pages, or screenshots, the file balloons. Compression works by re-encoding those images at a sensible quality, which can shrink a file dramatically while keeping it perfectly readable on screen.
Choosing the right compression level
There is always a trade-off between size and quality. A light setting keeps images crisp and is ideal when the document will be printed. A stronger setting produces the smallest file and is perfect for email attachments or upload forms with strict limits. If you are not sure, start with the balanced option, check the result, and only go heavier if you still need to save space.
Common size limits to keep in mind
- Many email providers cap attachments at around 25 MB.
- Government and job-application forms often ask for files under 1-2 MB.
- Some portals require a specific size such as 100 KB or 500 KB.
- Messaging apps compress differently, so send PDFs as documents, not photos.
How to use Compress PDF
- 1
Upload the PDF you want to shrink.
- 2
Pick a compression level to balance size against quality.
- 3
Download your smaller PDF.
Frequently asked questions
It depends on the content. Image-heavy PDFs compress the most; PDFs that are mostly plain text are already small and change little.