How to use the Compress PDF
- Choose a PDF.
- Pick a method: lossless first; strong compression if you need a much smaller file.
- Compress and compare the before/after size, then download.
Why PDFs are large
Most of a PDF's size usually comes from images — especially scanned pages and photos saved at high resolution. Text and vector graphics are tiny by comparison. That's why a 20-page scanned document can be 30 MB while a 200-page report is 2 MB.
The compression methods, honestly compared
- Lossless optimisation repacks the PDF's internal structure. It never changes how pages look and keeps text selectable, but savings are usually small (often under 10%). If no saving is possible, you get your original back.
- Strong compression re-renders each page as a JPEG image at a lower resolution. It can shrink scans dramatically, but text becomes part of the image — you can't select, search or copy it any more. Fine for scans and forms you're uploading; not for documents people need to search.
Other ways to get under a size limit
- Remove pages you don't need with Delete pages.
- Split a long document into parts with Split PDF.
- If you're creating a PDF from photos, compress the photos first with the image compressor.
Frequently asked questions
Why didn't my PDF get smaller?
Text-based PDFs (exported from Word, for example) are usually already compact. Lossless optimisation can't remove much; strong compression may even increase the size because rendered pages are images.
Is my PDF uploaded?
No. Both lossless and strong compression run entirely in your browser, so your PDF never leaves your device.
Will a government portal accept a strongly compressed PDF?
Usually yes, as long as it's readable. Check that small print is still legible before submitting; choose a sharper level if needed.