Most “compress PDF” results are websites. They work by uploading your file, compressing it on their servers and sending it back. That’s a lot of trust for a scan of your passport. These methods keep the file on your computer.
Why PDFs get big
Almost always it’s images: photos, scans and screenshots saved at high resolution. Fonts embedded in full and leftover data from editing add a little more. Text on its own is tiny, so compression is mostly about images.
On Windows or Mac: Paperwing
Paperwing is a free desktop app with a Compress PDF tool that runs offline.
- Download Paperwing and open your PDF.
- Open All tools and choose Compress PDF.
- Leave the algorithm on Condense (recommended) and the level on Balanced. Tick Convert to Grayscale if colour doesn’t matter.
- Run it. The compressed PDF opens in a new tab, so you can check it against the original.
- Save with Ctrl+S. If it’s still too big, try a stronger level.
To compress a whole batch, start Compress PDF from Paperwing’s Home screen and add every file at once.
On a Mac: Preview
Open the PDF in Preview, choose File, Export, and set Quartz Filter to Reduce File Size. It’s fast, but often too aggressive: images can come out noticeably blurry. Check the result before you send it.
Tips for a small file that still looks good
- Start gentle. Try a balanced level first and only go stronger if you have to.
- Grayscale helps a lot for scanned forms and receipts.
- Split before you compress if the upload form only needs a few pages: extract them first.
- Text stays sharp. Compression mainly affects images, so the words stay crisp even at strong levels.
- Scan at 200 to 300 DPI next time; anything higher mostly adds size.
Quick answers
Is it safe to compress a PDF online? It means uploading it. For anything personal, compress it on your computer.
How small can I get it? It depends on the content. Image-heavy PDFs often shrink by more than half; text-only PDFs are already small.
Does compression remove anything? It optimizes images, removes unused data and subsets fonts. Your text, links and pages stay.