How to reduce PDF file size
Most of a PDF's size is usually photos and scanned images. A PDF with many images can shrink noticeably when its images are re-saved, while a mostly-text PDF may barely change.
1. Why a PDF is large
- Photos or scanned pages are stored at high resolution.
- The same image appears many times.
- Fonts are embedded in full (usually a small effect).
2. Steps
- Add the file to Compress PDF. The tool on this site re-saves the photos and scanned images inside the PDF and shows the size before and after.
- Save the result.
- Keep the original file.
3. Check afterwards
- Zoom in: is the text still readable, and are stamps, signatures and photos still clear?
- For submissions, check that the file is now under the receiving site's limit.
- Files with few images may barely shrink. In that case, re-creating the PDF from the source document with lower-resolution images can help (saving each page as a picture can make the text unsearchable and uncopyable).
4. Another way to shrink
Saving only the pages you need also reduces size. → How to save only some pages of a PDF
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