Compress PDF online - reduce PDF file size for email and uploads

The tool rasterizes your document: every page is drawn at the chosen resolution (DPI), saved as a JPEG at the chosen quality and placed into a new PDF with exactly the same page dimensions. This is very effective for scans, phone photos of documents and image-heavy brochures, which often weigh 20-50 MB because the scanner saved them at 300-600 DPI.

The trade-off: after compression the text is part of a picture. You cannot select, copy or search it, and links, bookmarks and form fields stop working. Do not use this method on a contract you still need to edit or on a report people will search - keep the original and send the compressed copy only where a size limit forces you to.

Documents that are mostly text (for example a Word export) are usually small already, and turning them into images can make them bigger. In that case the tool tells you so and keeps the original untouched.

• Strong - 72 DPI, JPEG quality 50%. The smallest file, visibly softer. Fine for on-screen reading and strict upload limits.
• Recommended - 110 DPI, JPEG quality 70%. A good balance for email, job portals, bank and government forms.
• Light - 150 DPI, JPEG quality 85%. Readable when printed and with small print, but saves less.
• Custom - move the sliders: resolution from 50 to 200 DPI, quality from 20% to 95%.

For reference, an A4 page is about 595 × 842 px at 72 DPI, 909 × 1286 px at 110 DPI and 1240 × 1754 px at 150 DPI. A US Letter page at 110 DPI is about 935 × 1210 px. File size grows roughly with the number of pixels, but it also depends on the content - a full-page photo weighs far more than black text on white paper. Very large pages are capped at about 16 megapixels to keep the browser from running out of memory.

• Start with Recommended. A 10-page scan that weighed 30 MB typically drops to 1-3 MB.
• Still too big? Switch to Strong, or set about 90 DPI and 60% quality yourself.
• Below roughly 100 DPI small printed letters on an A4 or Letter page start to blur, so check the result before sending an important document.
• For very long documents, consider cutting the file into parts with Split PDF and sending them separately, or removing unneeded pages first in Organize PDF.
• If you are building a PDF from photos, shrink the photos first in the image compressor - then the text pages can stay sharp.

Rendering and compression run entirely in your browser with pdf.js and pdf-lib. Nothing is uploaded, so you can safely compress scanned IDs, medical results or signed contracts. Speed depends on your device: a 20-page scan usually takes a few seconds on a laptop and somewhat longer on an older phone.

Password-protected PDFs can be compressed if you know the password. The result is a brand-new document built from images, so it is no longer password-protected - keep that in mind before sharing it.