# Compress EPUB

> Compress Electronic Publication (EPUB) files online for free. The compressor shrinks the embedded images and repacks the book at maximum compression; the text is untouched. Processed in an isolated cloud sandbox and deleted automatically. Or set an exact target size.

URL: https://www.converterrr.com/compress-epub

- Compression: lossy, runs in an isolated cloud sandbox (deleted automatically).
- API: `POST /api/v1/jobs` with `"operation": "compress"` and an optional `compression_level` or `target_size` (paid plans).
- Format: [EPUB converter](https://www.converterrr.com/epub-converter), [Compress documents](https://www.converterrr.com/compress-documents).

## What compression does to EPUB

Shrinks the embedded images and repacks the book at maximum compression; the text is untouched.

- **Light:** Gentle: images are recompressed but stay close to the original; good for print.
- **Balanced (default):** The default: images are optimised for reading on screen, usually with no visible difference.
- **Strong:** Smallest file: images are downsampled further; fine on screen, not for print.

## How to compress EPUB

1. **Add your EPUB files.** Drag and drop EPUB files onto the compressor, paste them, or click to browse. You can add several at once.
2. **Pick a level or a target.** Balanced is selected and suits most files. Choose Light to stay closer to the original or Strong for the smallest file, or set a target size or a percentage to reduce by.
3. **Compress.** Click Compress. Files are processed in an isolated cloud sandbox and are usually ready in seconds.
4. **Download.** Download each smaller EPUB, or everything at once as a ZIP.

## Good to know

- An EPUB is a ZIP of HTML chapters, stylesheets, fonts and images. The cover and illustrations are usually most of its size; those are shrunk and the text is untouched.
- A smaller EPUB is quicker to email, sync and send to an e-reader.
- Need to meet an upload limit? Set a target size (or a percentage to reduce by) in the compressor and the eBook is compressed to fit.
- EPUB files are compressed in an isolated cloud sandbox created just for your job; the upload and the result are deleted automatically afterwards.

## About the EPUB format

EPUB is the open standard e-book format with reflowable text, supported by Apple Books, Kobo, Google Play Books and Kindle (via Send to Kindle).

|  | EPUB |
| --- | --- |
| Full name | Electronic Publication |
| Type | eBook |
| Extensions | .epub |
| MIME type | application/epub+zip |
| Best for | e-books on almost every reader |
| Properties | open standard |

## Compress other documents

[Compress PDF](https://www.converterrr.com/compress-pdf), [Compress DOCX](https://www.converterrr.com/compress-docx), [Compress PPTX](https://www.converterrr.com/compress-pptx), [Compress XLSX](https://www.converterrr.com/compress-xlsx), [Compress ODT](https://www.converterrr.com/compress-odt), [Compress ODP](https://www.converterrr.com/compress-odp), [Compress ODS](https://www.converterrr.com/compress-ods)

## Compressing EPUB: frequently asked questions

### How do I compress an EPUB file?

Drop the EPUB onto the compressor above, keep Balanced or pick another level, and click Compress. Download the smaller EPUB when it's done; it usually takes a few seconds.

### Does compressing EPUB reduce quality?

A little, by design: EPUB is a lossy format. Balanced is tuned to look the same for most uses; choose Light if you want to stay closer to the original.

### How much smaller will my EPUB get?

Illustrated books and comics shrink the most; text-only EPUBs are already small.

### Can I compress EPUB to a specific size?

Yes. Set a target size in the compressor, or a percentage to reduce by, and the file is compressed to land at or just under it.

### Is it safe to compress EPUB files here?

Yes. Your file travels over an encrypted connection to an isolated sandbox created for your job only, and both the original and the result are deleted automatically.

### Is the EPUB compressor free?

Yes. Cloud jobs like this one use the same free daily credits as cloud conversions, and there's no watermark.