How to reduce the size of a PDF file

Last updated: 21 October 2026

Email services and online forms often limit attachments to a few megabytes. A large PDF is usually large because of images: scans, photos or high-resolution graphics. Text alone rarely makes a PDF big.

Choose the right compression level

• Basic keeps everything as it is and rewrites the file more efficiently. Text stays selectable and searchable. Best for documents created from Word or similar programs.
• Strong turns each page into an image at 150 DPI. This gives a much smaller file for scans and photo-heavy documents, but the text can no longer be selected.
• Extreme uses 100 DPI and stronger image compression for the smallest possible file. Use it when the size limit matters more than image quality.

Step by step

1. Open the Compress PDF tool and select your file.
2. Pick a compression level. Start with Basic for text documents and Strong for scans.
3. Click Compress PDF. You see the size before and after, and the smaller file downloads automatically.
4. If the file is still too large, try the next level.

If compression would make the file bigger, compare2pdf keeps your original file and tells you, so you never end up with a worse result.