Which compression level should you choose?
Each level sets how much detail the images keep. Lower DPI means a smaller file, but photos look softer when you zoom in.
| Level | Image resolution | Best for |
|---|---|---|
| Strong | about 72 DPI | Strict upload limits, chat apps, quick previews |
| Recommended | about 150 DPI | Email, reading on a screen, most forms |
| Light | about 300 DPI | Printing, documents with small details |
Start with Recommended. Still too big? Try Strong. If a stamp or a photo looks blurry, go back to Light. Your original is not changed, so you can run the same file again at another level.
Why some PDFs are so large
A PDF exported from Word or Google Docs is mostly text, and text takes very little space. A scanned contract is different: every page is a full photo of paper, often in color and at high resolution.
That is why a 10 page scan can outweigh a 200 page ebook. Shrinking those page images gives the big savings, while a text only PDF may barely change.
If a form names an exact limit, the size presets pick the level for you. Try Compress PDF to 200 KB or Compress PDF to 1 MB. For the strictest forms, compress PDF to 100 KB in one go.
More ways to compress PDF files
Remove what nobody needs. Blank scanner pages, duplicates and long appendices all add weight. Cut them out first, or send only the relevant part with Split PDF.
When you scan, choose grayscale for plain text documents. A gray page compresses far better than a color one, and many phone scanner apps also let you pick a lower resolution.
Think about the reader too. A document headed for a printer deserves Light, while a form that only has to be readable on screen is fine with Strong.