Compress a PDF and reduce its file size
Shrink PDF file size with three quality presets or a lossless clean-up re-save. See the before and after size and percentage saved instantly.
- Runs in your browser
- Files are never uploaded
- Free, no account
How to compress a PDF
- Drop the PDF onto the box above.
- Choose a mode. Quality presets re-render every page as a JPEG at a set resolution — that is where the big savings are. Lossless clean-up rebuilds the file structure without touching the page content.
- Press Compress PDF and watch the per-page progress.
- Compare the before and after sizes, then download. If it is not small enough, drop the DPI and run it again.
What each preset actually does
| Preset | Resolution | JPEG quality | Best for |
|---|---|---|---|
| Strong | 72 DPI | 50 | Screen-only reading, email attachments with a hard size cap |
| Recommended | 110 DPI | 62 | The everyday choice: readable on any screen, still legible printed |
| Light | 150 DPI | 80 | Documents that will be printed or archived |
| Lossless clean-up | unchanged | n/a | Text documents where search and copy must keep working |
A page at 110 DPI is roughly 900 × 1270 pixels for A4 — enough that body text stays crisp on a laptop screen and on a phone. At 72 DPI it is 595 × 842 pixels, which looks fine at normal zoom but shows softening on small print. Custom mode exposes both dials if you want to aim at a specific size.
Why some PDFs barely shrink
File size in a PDF is almost always dominated by images. A 40-page report exported from a word processor might be 300 KB in total, because text is stored as a few kilobytes of font references and drawing operators per page — there is nothing left to squeeze. A single scanned page from a phone camera, by contrast, can be 3 MB on its own.
- Scans and photos: expect 70-95% smaller with the Recommended preset.
- Slide decks with photos: typically 50-80% smaller.
- Text-only documents: a few percent at best, and rasterising them makes the file bigger, not smaller — use lossless clean-up instead.
- Already-compressed scans: if a scanner has already saved JPEGs at 100 DPI, re-encoding gains little and costs quality.
Greyscale conversion is worth trying on colour scans of black-and-white originals: dropping the chroma channels usually removes another 20-30% without changing readability.
The trade-off, stated plainly
Rasterising is a one-way conversion. After it, the page is a picture: you cannot select or search the text, links stop working, form fields are flattened and screen readers can no longer read the content. That is the same thing every "extreme compression" button on other sites does, but it is rarely spelled out. Keep the original if any of that matters, and use the lossless mode when the document must stay accessible.
Questions
What is the difference between the two modes?
Lossless clean-up rewrites the file structure and drops unused objects — text stays selectable but savings are modest. Quality presets rasterise each page to a JPEG at a chosen DPI, which shrinks scans dramatically but makes text an image.
Which preset should I pick?
Recommended (110 DPI) is a good default for email and web. Use Strong (72 DPI) for a document that will only be read on screen, and Light (150 DPI) when the file may be printed.
Why did my file barely get smaller?
PDFs that are mostly text and vectors are already tiny per page — there is little to squeeze. Big savings come from scanned or image-heavy documents, where the images dominate the file size.
Will text still be searchable after compressing?
Only in lossless clean-up mode. The quality presets convert each page to a picture, so selectable text, links and form fields are flattened away.
Is anything uploaded to a server?
No. Rendering and re-encoding happen with WebAssembly and canvas inside this tab, so the document never leaves your device.