Compress PDF
Reduce PDF file size by re-rendering pages at lower quality, all in your browser
Get a Scanned PDF Under Your Email Provider's Size Limit
Most email providers cap attachments somewhere around 20-25MB, and a scanned contract or a PDF exported from a phone's document scanner can blow past that without much effort, especially once it's a dozen pages of high-resolution photos. This tool brings that file down by re-rendering every page through PDF.js at its original resolution, then re-encoding the result as a JPEG at the quality level you choose, before reassembling everything into a new PDF with pdf-lib. The quality slider is the only control that matters: 70% is a reasonable middle ground that usually cuts file size by 60-80% while still looking sharp on a screen, 50% pushes for the smallest possible file when size matters more than appearance, and 90% keeps things close to the original for documents you might print.
Because every page gets rendered to an image and re-encoded, this approach works best on PDFs that are already image-heavy: scanned documents, exported photo collections, or design proofs. A PDF made up mostly of typed text behaves differently, since the text itself gets rasterized into the JPEG along with everything else. At quality settings of 70% and above this is rarely noticeable on screen, but zooming in on small text at lower quality settings can show the same kind of softening you'd see in a compressed photograph. If a document is mostly text and the file size is the issue, check whether the bulk of the size is actually coming from embedded images or scanned pages first, since that's where this tool makes the biggest difference. After compression, the original and new file sizes are shown together so you can see whether the trade-off was worth it before relying on the result.
How to Use
- 1
Upload the PDF
Any standard, unencrypted PDF works. Scanned documents and PDFs full of photos or design proofs see the largest size reductions.
- 2
Set the quality slider
70% is a solid default. Drop to 50% if you need the smallest file regardless of appearance, or raise to 90% if the document might get printed.
- 3
Run the compression
Each page is rendered and re-encoded in your browser, then rebuilt into a new PDF file.
- 4
Compare sizes before sending
The original and compressed sizes are shown side by side, so you can confirm the file now fits under your email provider's attachment limit.
Key Features
- →70% quality is a good starting point: usually a 60-80% size reduction with no obvious loss on screen.
- →Scanned pages and photo-heavy PDFs compress the most because most of their size comes from images to begin with.
- →Documents that are mostly typed text benefit less, since the text gets rasterized along with the rest of the page.
- →If 50% quality looks too rough on small text, step back up to 65-70% rather than going lower.
- →Check the before and after file sizes shown after compression to confirm it's actually small enough before attaching it.
Frequently Asked Questions
My PDF is still too big for email after compressing. What else can I try?
Try a lower quality setting first. If the document has pages you don't actually need to send, removing them with the PDF Editor before compressing reduces the page count, which compounds with the per-page size reduction.
Will compressing make the text in my PDF blurry?
At 70% quality and above, text usually still looks sharp on screen because the rasterization happens at the page's original resolution. Below about 50%, small text can start to look soft, especially if you zoom in.
Why doesn't compression help much with my text-only PDF?
The compression works by re-encoding each page as a JPEG image, which mainly benefits pages where photos or scans already account for most of the file size. A text-only PDF is small to begin with, so there's less to gain.
Is it safe to compress a PDF that contains personal or financial information?
Yes. The whole process, rendering, compressing, and rebuilding the PDF, happens in your browser using PDF.js and pdf-lib. The file is never sent anywhere, which matters for contracts, statements, or ID scans.
Last updated: June 2026