How to Reduce EPUB File Size
Large EPUB files can be slow to load on e-readers and take up unnecessary storage. Here's how to reduce EPUB file size without losing quality.
What Makes EPUBs Large?
- Images — High-resolution images are the #1 cause of large EPUBs
- Embedded fonts — Custom fonts can add 1-5MB each
- Uncompressed files — Some EPUB generators don't optimize the ZIP compression
Compress Your EPUB Online
- Go to Compress EPUB
- Upload your file
- Choose compression level: Low (fast), Medium (balanced), or Maximum (smallest file)
- Download your compressed EPUB
Our tool recompresses images using modern codecs and optimizes the ZIP structure. Typical savings: 30-70%.
Advanced Tips
- Remove unused CSS with EPUB validation
- Convert PNG images to JPEG where transparency isn't needed
- Subset fonts to include only used characters
Related Guides
- How to merge EPUB files — combine before compressing
- Convert EPUB to PDF after optimizing
- Edit EPUB metadata
- All free EPUB tools
Try it now — free
Reduce EPUB file size by up to 70% while preserving quality. Compress images, optimize fonts, minimize your ebook. Free online tool.
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