How the free online ebook converter works
Most e-book formats are close relatives: each is a set of chapters written as web pages, with a table of contents, a cover and some styling. Converting between them properly means rebuilding the book for the target reader, which is exactly what Calibre does. Calibre is the free, open-source e-book manager that millions of readers use on their own computers, and this converter runs it on our server so you do not have to install anything.
The book is uploaded to a private temporary folder used only for this conversion, converted, and deleted together with the result as soon as the result reaches your browser. Books with DRM, which most stores add to purchases, are encrypted and cannot be converted by any honest tool. DRM-free books from Project Gutenberg, Standard Ebooks, independent authors and many publishers convert normally.
Which ebook format should you use?
EPUB is the universal e-book format. Apple Books, Google Play Books, Kobo, most library apps and nearly every Android reader open it, and Amazon's Send to Kindle now accepts EPUB too, converting it for the Kindle on the way. If in doubt, choose EPUB.
AZW3 is the Kindle's own modern format, the one to use when copying a book to a Kindle over USB. MOBI is its older predecessor, still read by older Kindles and the Kindle apps but no longer accepted by Send to Kindle.
PDF gives fixed pages that print well and look the same on every screen, but they do not reflow, so small text on a phone means zooming. Converting a PDF to EPUB is the reverse trip, which works best for simple books made from a text document.
Common ebook conversions and why people need them
The common jobs are EPUB to AZW3 or MOBI for a Kindle, MOBI or AZW3 to EPUB for Kobo, Apple Books or a library app, FB2 books from Russian and Eastern European libraries to EPUB, and e-books to PDF for printing or reading on a laptop.
Calibre carries over the chapters, headings, images, cover and table of contents, and keeps the book's own styling. The reading app then decides the font and size, which is the point of an e-book. When the source is a PDF, Calibre has to rebuild flowing text from fixed pages, which works well for novels and less well for textbooks with columns, footnotes and tables.
Ebook formats compared
| Format | Compression | Best for |
|---|---|---|
| AZW | Lossless | Kindle books from the first Kindle onwards |
| AZW3 | Lossless | Kindle e-readers and books loaded onto them over USB |
| CBC | Lossless | comic series and volumes kept together as one file |
| CBZ | Lossless | digital comics, manga and scanned magazines |
| CHM | Lossless | Windows help files, software manuals and some older e-books |
| EPUB | Lossless | e-books from stores other than Amazon and free e-book libraries |
| FB2 | Lossless | e-books from Russian and Eastern European libraries |
| LIT | Lossless | e-books bought or downloaded for Microsoft Reader in the 2000s |
| LRF | Lossless | books bought for the first Sony Reader e-readers |
| MOBI | Lossless | older Kindle e-readers and e-books from the 2000s |
| PDB | Lossless | e-books for Palm handhelds and old eReader purchases |
| PRC | Lossless | Mobipocket books for Palm and Pocket PC devices, and early Kindle downloads |
Tips for converting ebook files
- For a current Kindle, send EPUB through Send to Kindle, or copy AZW3 over USB.
- Books bought from Amazon, Kobo or Apple usually have DRM and cannot be converted.
- For PDF to EPUB, use a PDF made from a text document, not a scan.
- Keep the original file; each conversion rebuilds the book.
Is it safe to convert ebook files online?
These conversions need an office suite or an e-book engine, which cannot run inside a browser, so unlike most of TapToConvert they use our conversion server. Here is exactly what happens to your file. It is sent over an encrypted connection to a private temporary folder that only this conversion uses. The converter works on it there, the result is streamed straight back to your browser, and the folder is deleted, with your file and the result inside it, the moment the result has been sent.
Nothing is stored afterwards, there is no account that files are attached to, and our logs record only the formats, the size and whether the conversion worked, never file names or contents. Any folder left behind by a failed conversion is removed automatically within ten minutes. If a file is too sensitive to leave your computer at all, install the same free program and convert it there; the commands are on each conversion page.
Ebook Converter FAQ
Can I read EPUB on a Kindle?
Yes, through Send to Kindle, which accepts EPUB. To copy a book over USB, convert it to AZW3 first.
Why will my Kindle book not convert?
Books bought from Amazon usually have DRM, which encrypts them. No legitimate converter removes DRM.
Is my book stored on your server?
No. It is deleted together with the result as soon as the result has been sent back to you.
Which is better, MOBI or AZW3?
AZW3. It supports modern styling, and MOBI is no longer accepted by Send to Kindle.
Is the ebook converter free?
Yes, with no sign-up and no watermark. Conversions that use our server accept files up to 25 MB each, with a fair-use limit per hour so the service stays fast for everyone. The site is supported by advertising.
Does the ebook converter work on phones?
Yes. It works in Safari on iPhone and iPad and in Chrome on Android. Converted files are saved to your Downloads folder.