Ebook Converter

The ebook world is split mainly between EPUB and Amazon's own formats. EPUB is an open standard, so most readers and apps outside the Amazon ecosystem open it directly: Kobo, Nook, PocketBook, Apple Books, Google Play Books and many free reading apps on Android, iOS and desktop computers. Kindles use Amazon formats. AZW3, also known as Kindle Format 8, supports modern layouts, embedded fonts and better image handling, and it is what to choose when you copy a book onto a Kindle with a USB cable. MOBI is the older Kindle format with simpler formatting; it is only worth picking for early Kindle models that cannot read AZW3.

Amazon's Send to Kindle service, which delivers books to your Kindle library by email, app or browser upload, accepts EPUB files and converts them for the device. Since 2022 it no longer accepts MOBI files for sending, which surprised many people with older libraries. In practice, that means an EPUB is now the most flexible single copy of a book: it works for almost every reader directly and for Kindles through Send to Kindle. Keep AZW3 for cable transfers and for readers who prefer not to use their Amazon account.

FB2, or FictionBook, is an XML-based format popular in Russian and Eastern European ebook libraries. Converting it to EPUB opens those books on any mainstream reader. Plain text, Word documents and HTML files can also become ebooks, which is useful for reading your own drafts, long reports or saved articles on an e-ink screen.

Getting the finished file onto a device is the last step. Most e-readers appear as a drive when connected to a computer with a USB cable, and books copied into their documents folder show up in the library. Kobo and Nook readers take EPUB this way, and Kindles take AZW3. Reading apps on phones and tablets usually import a book when you open the downloaded file and choose the app from the share menu. Cloud libraries such as Google Play Books let you upload EPUB and PDF files from a browser and read them on every device signed in to the same account.

Writers use the same path in reverse. A manuscript in Word or Markdown can become an EPUB to proofread on the device readers will actually use, which shows awkward page breaks, oversized images and missing headings long before publication. Set the Title and Author fields so the test copy is easy to find in the library.

Comic book archives are simpler than they look. A CBZ file is a ZIP archive of page images, and a CBR is the same idea packed with RAR. Comic readers open them page by page, in file-name order. The converter reads CBZ, CBR and CB7, writes CBZ, and can also turn a set of JPG, PNG or WebP images into a single book: upload the pages, leave Combine images into one book on and choose CBZ, EPUB or PDF. Give the files numbered names first, such as 001 and 002, so the pages come out in the right order.

For e-ink readers, Grayscale images turns every page to gray before it is saved. Most e-ink screens show gray anyway, so the picture looks the same while the book takes up less space. Image quality controls the JPEG compression of the pages; the default of 85 looks clean on e-ink, and lowering it makes large comic collections lighter.

PDF works in both directions, with a catch. Turning an EPUB into a PDF gives fixed pages for printing and annotating; set PDF page size to A5 for something close to a paperback, or match the reading device so each page fills the screen. Turning a PDF into EPUB lets the text reflow on a small screen, which works well for novels and other plain text but can lose the layout of magazines, textbooks and designed pages. For PDFs that only need to be smaller or split, the PDF tools are a better fit, and the Document Converter page handles editable office formats.