Compress CBZ and CBR files
A high-resolution comic archive can easily run past a few hundred megabytes, which is a problem when Send-to-Kindle refuses anything over 200 MB, or when a phone is running low on space. Compressing re-encodes the page images to a smaller total size while keeping them readable, so the same volume fits where it did not before.
↑ Upload and configure in our Studio
This page presets a size target of 200 MB and repacks to CBZ. Drop your archive, and the pages are re-encoded to land under the cap. Prefer a book format instead? Switch the output to EPUB or a device profile and the same size target still applies.
- Files auto-delete after 24 hours
- No install, runs in any browser
- Free to use
- The genuine open-source KCC engine
How to compress a CBZ or CBR
Drop your archive
Drag in a CBZ, CBR, ZIP, RAR or 7Z. Large files are fine, that is the point. Several queue and convert in turn.
A size target is already set
The output is preset to aim under 200 MB, the Send-to-Kindle ceiling. The pages are re-encoded to reach that size while staying readable.
Keep CBZ or pick a format
The output is preset to repack as a smaller CBZ. Switch to EPUB, MOBI or a device profile if you would rather have a book file, the size target carries over.
Convert and download
Convert, then download the smaller file. It now fits the Kindle mail limit or your storage. Files auto-delete after 24 hours.
The 200 MB Kindle ceiling
Send-to-Kindle by email or app caps files at 200 MB. This page targets just under that, so a compressed volume transfers cleanly where the original bounced.
Compress for reading, keep the original
If a volume is a prized scan, keep the full-resolution archive and compress a copy for the device. The reading copy fits your reader, the archive keeps every pixel.
Frequently asked questions
Why does my CBZ need to be under 200 MB?
Amazon Send-to-Kindle, whether by email or the app, rejects files larger than 200 MB. A big scanned volume often exceeds that, so it never reaches the device. Compressing brings it under the cap so the transfer succeeds.
Will compressing ruin the quality?
The pages are re-encoded to reach the target size, so there is some reduction, but the goal is a file that still reads cleanly on an e-ink screen. Text and line art stay legible. If you need pixel-perfect archival quality, keep the original and compress a copy for reading.
Can I compress a CBR?
Yes. CBR, ZIP, RAR and 7Z archives all work as input. The output repacks to CBZ by default, which every comic reader opens.
What if I want a different target size?
The page presets 200 MB because that is the Kindle mail limit. You are choosing the output here rather than a fixed size, so pick a device format if you want the converter to size to a screen instead of to a byte budget.
Is it free?
Yes. The free tier handles typical single volumes, and the work runs on our servers, so a phone compresses a large file as fast as a desktop would.
The re-encoding runs on Kindle Comic Converter (KCC), the open-source engine comic readers have trusted for years, hosted for you so there is nothing to install.
Free, no install, a 200 MB size target is preset for you