Compress a copy and check a full page
Keep the original PDF. Upload a copy to the PDF compressor and download the result. Open the compressed file at 100% zoom and read a full page, not just the thumbnail.
Use this check:
- Body text is sharp at normal reading size
- Small print, footnotes, and table labels are legible
- Chart lines and table borders are unbroken
- Scanned pages are clear enough to read without zooming far in
If the compressed file fails any check, keep the original or try a lighter compression setting if one is available.
Know what compression can and cannot do
PDF compression usually reduces file size by re-encoding images and removing redundant data. Digital text normally stays sharp because it remains text.
Compression does not repair a poor scan, improve blurry source images, or guarantee a specific file size. A scanned PDF may become harder to read because the page is an image.
Stop at the smallest readable file
Compare the compressed file with the original on the device your readers will use. A phone screen is a useful test for small text.
Use the smaller file only when it still meets your reading needs. For printing or archiving, keep a higher-quality copy; for email or web upload, a readable compressed copy is usually enough.