Compress PDF
Shrink a PDF for email or upload without wrecking quality. Free, private and done entirely in your browser — nothing is uploaded.
or drag and drop it here
How to compress a PDF
- Drop your PDF onto the page.
- Pick a level. Light rewrites the file structure and keeps text selectable. Medium and Strong re-render each page as an optimised image, which gives much smaller files for scans and photo-heavy documents.
- Click Compress PDF, check the before/after size and download.
Which level should I choose?
For text documents you plan to edit or search, use Light. For scanned paperwork, slide decks or brochures you just need to email, Medium usually gives a large saving while keeping pages readable, though results depend on how image-heavy the file is. Strong is best when a strict upload limit matters more than image sharpness.
Privacy
Compression runs on your device — your PDF is never uploaded.
Compress PDF: what compressing a PDF actually does
To compress a PDF means rewriting it so the same pages take up fewer bytes. How much you can save depends mostly on what is inside the file. Photos and scanned pages are large and can usually be shrunk a lot. Plain text and vector drawings are already compact and often have very little to give.
The three levels here work in two different ways. Light opens the PDF and re-saves it with a tidier internal structure. Nothing on the page changes, so text stays selectable, but the saving is often small and some files barely change at all. Medium and Strong redraw every page as a JPEG image and build a new PDF from those images. That is where large reductions on scans come from, but the trade-off is real: the pages become pictures, so text can no longer be selected, searched or copied, and links and fillable form fields are lost.
What each compression level does
| Level | How it works | Page image size (A4 page) | Text selectable? | Best for |
|---|---|---|---|---|
| Light | Re-saves the file structure; page content untouched | Original content kept | Yes | Text documents, forms, files you will edit or search |
| Medium | Renders each page at 1.3× (about 94 DPI), saves as JPEG at 72% quality | About 774 × 1094 px | No | Scans, slide decks and brochures to email |
| Strong | Renders each page at 1× (72 DPI), saves as JPEG at 55% quality | About 595 × 842 px | No | Strict upload limits where sharpness matters less |
Pixel sizes are for an A4 page (210 × 297 mm); a US Letter page (8.5 × 11 in) works out slightly wider and shorter. Page dimensions stay the same after compression, only the image detail inside them changes. Actual savings vary from file to file, which is why the tool shows the before and after sizes so you can judge for yourself.
Two examples: a scan vs a text document
A 10-page scanned document
Office scanners and scanning apps often store each page as a photo at 200 to 300 DPI. A 300 DPI page has about ten times as many pixels as the same page at 94 DPI ((300 ÷ 94)² ≈ 10.2). Medium redraws each page at about 94 DPI and saves it as a JPEG, so image-heavy scans usually shrink noticeably. After downloading, zoom in on the smallest print, signatures and stamps to make sure they are still readable before you send the file.
A report exported from Word or Google Docs
Here the text is stored as fonts and vector shapes, which take very little space. Light may save a little or nothing. Medium or Strong can even produce a larger file, because a page of crisp text turned into a picture can take more bytes than the text did. If the After figure is not smaller than Before, keep your original.
Tips before you compress
- Keep the original. Medium and Strong can’t be undone, because the text layer is replaced by images.
- Try Medium first and step up to Strong only if you are still over the size limit.
- Check small print after compressing. At 72 DPI, fine text such as footnotes or table figures can blur.
- If only a few pages are heavy (photos in an appendix, for example), split them out, compress just those, then merge the parts back together.
- Don’t use Medium or Strong on forms you still need to fill in or documents where readers need to search or copy text.
- Compressing the same file twice at the same level rarely gains much and costs more quality.
More questions
How do I compress a PDF to under 1 MB or 200 KB?
There is no exact target-size setting. Try Medium and check the After size, then Strong if needed. If it is still too big, split the file and send it in parts, or drop pages you don’t need. Long scans may not reach very small sizes while staying readable, so check the result before uploading.
Why is my compressed PDF bigger than the original?
This mostly happens with text-based PDFs on Medium or Strong. The text is turned into an image, and that image can be heavier than the compact original. Use Light for these files, or simply keep the original.
Does compressing a PDF reduce quality?
Light doesn’t change what is on the page. Medium and Strong do: pages become lower-resolution JPEG images, so text looks softer when you zoom in and can’t be selected. For on-screen reading and emailing that is often acceptable, but always check the result yourself.
Can I compress a PDF on my phone?
Yes, it works in mobile browsers. Large scans with many pages take longer and need more memory; if the tab stalls or reloads, try on a computer or split the file into smaller parts first.
Related tools: shrink photos before putting them in a PDF with Compress Image, separate heavy pages with Split PDF, or recombine the parts with Merge PDF.
Further reading: PDF (Wikipedia).