Compress PDF

Compress PDF: uses and practical guidance

Compressing a PDF helps when a document is too heavy to email, upload to a form or keep on a phone. Most of a PDF’s weight usually comes from embedded photographs rather than text. This tool re-encodes the document’s JPG photos at a lower quality and reduces their resolution when it exceeds what a screen or ordinary print needs. Text, vector graphics and every other object are left unchanged, and the whole process runs in your browser.

Choose the level according to the destination. Gentle keeps nearly all detail and suits documents that will be printed. Balanced is the recommended option for email and forms: it usually cuts the size substantially without an obvious difference at normal viewing size. Maximum compression prioritizes file weight and can show artifacts in photographs with fine detail; use it for drafts or reading on small screens. If the result is not satisfactory, start again from the original file, because compressing an already compressed output repeatedly accumulates quality loss.

The tool may report that the file is already optimized. That happens with text-only documents, with images that are already heavily compressed, or with scans stored in formats that are not recompressed here, such as high-resolution black and white. In that case no file is created, so you are not handed a copy that is larger than or equal to the original. Encrypted PDFs are not supported, and modifying a document invalidates its digital signatures. Always compare a page containing photographs before and after sharing the result.

A practical check before using the result

Try a PDF that contains photographs and note its size before and after. Open a page with photos in both the original and the copy and compare edges, gradients and overlaid text. If the notice says some images were not recompressed, that is expected: only embedded JPG photos are processed. Also confirm that the copy keeps the page count and that the links you need still work.