Compress PDF DocWhy Is My PDF So Large?
The usual suspects behind huge PDFs, and the quickest fix for each.
1. It is a scan
Scanned pages are photos of paper. At 300–600 DPI in color, one page can be several megabytes. Fix: compress on Recommended or Extreme, and use grayscale for black-and-white documents.
2. Photos at full camera resolution
A 12-megapixel photo placed in a small box on the page is still stored at 12 megapixels. Fix: the compressor downsamples each image to the size it is actually displayed.
3. Images stored without lossy compression
Some apps embed screenshots and photos losslessly (Flate). Re-encoding them as JPEG at sensible quality often saves 90%.
4. Embedded fonts
Full fonts, especially CJK fonts, can add megabytes. Fonts are kept so text looks right; our compressor removes duplicate fonts and slims unused tables.
5. Duplicate objects
Merged PDFs often contain the same logo or font many times. Duplicates are detected and merged automatically.
6. Metadata, thumbnails and leftovers
Edit history, XMP metadata, page thumbnails and unreachable objects build up as a file is edited and re-saved. They are removed on compression.
7. Print-ready CMYK images
Print PDFs carry large CMYK images. For screen and email they can be converted to RGB and recompressed: our 3-page CMYK test PDF went from 10.9 MB to 454 KB. Keep the original for the printer.
Ready to fix yours? Use the free PDF compressor.
Frequently asked questions
Related
Compress PDF Online
Reduce PDF file size up to 95% in your browser. No upload, no limits, no sign-up.
How to Reduce PDF File Size
8 ways to make a PDF smaller while keeping text sharp and links intact.
How to Compress a PDF for Email
Attachment limits for Gmail and Outlook, and how to get under them fast.