Convert ePub to MOBI

Turn an ePub into a MOBI file to copy onto a Kindle by USB cable. No signup; runs on our server, and files are deleted within about two hours.

Drop your files here

.epub · up to 200 MB · up to 30 jobs an hour · uploaded to our server and deleted after processing; the result is wiped within about two hours

Choose files

Old (MOBI 6, older readers)New (KF8/AZW3-compatible)Both (most compatible)

More settings

Title (optional)Author (optional)Keep cover

How to convert ePub to MOBI for Kindle

1
Add your ePub
One .epub file up to 200 MB. A book protected with DRM is refused before the conversion starts.
2
Choose the MOBI file type
Both, the default, holds the old and the new Kindle format in one file. Title and Author are optional: left blank, they come from the ePub.
3
Download it and copy it to your Kindle
Connect the Kindle by USB and copy the .mobi into its Documents folder. Send to Kindle does not take MOBI: to email the book, send the ePub itself.

From ePub to Kindle: when you need MOBI

Amazon offers two ways to put your own ePub on a Kindle, and only one of them needs this converter. Send to Kindle, Amazon's service for the web, the Kindle app, email and desktop apps, takes the ePub itself and converts it on Amazon's side. As of October 2026, its list of formats has EPUB and no MOBI. A USB cable is different: the Kindle opens the file as it is. Amazon's specifications for current Kindle e-readers list unprotected MOBI among the formats read natively, and EPUB only through conversion. That is the case this page is for.

What the conversion changes in the book

Calibre's ebook-convert does the conversion. The table of contents comes from the ePub, and a contents page is added at the start of the book unless the ePub has one. The cover named in the ePub becomes the MOBI cover. Title and author come from the ePub unless you type your own. Pictures are saved again as JPEG, so a transparent background turns white. Fonts embedded as TTF or OTF files go only into the newer KF8 part: Both and New keep them, Old leaves them out. Before the download appears, the server checks the file's MOBI header and reports a failure as an error. To go back, MOBI to ePub takes the result without picking the file again; the pictures stay JPEG.

Old, New or Both: choosing the MOBI file type

Calibre's manual puts it this way: MOBI 6, the Old type, is compatible with all devices; KF8, the New type, has more features but works only with newer Kindles. Both writes the two into one .mobi file, which is why it is the default. New gives a KF8-only file, the format Amazon calls AZW3, under a .mobi name. Old skips the KF8 part: try it if a long, picture-heavy book runs past the three-minute conversion limit.

Processed on our server, deleted automatically

Writing a MOBI file takes Calibre's conversion engine, so this tool runs on PulsarKit's server rather than in your browser. Calibre works in a temporary folder that is removed as soon as the job ends, and the uploaded ePub is deleted at the same moment, whether the conversion worked or not. The MOBI stays downloadable for one hour and is wiped from the server within about two hours, whether or not you download it.

Frequently asked questions

Does Kindle read ePub files?

Only through conversion. Amazon's specifications for its Kindle e-readers list EPUB among the formats read through conversion, not natively. That conversion is Send to Kindle: send the ePub by web, app or email, and it arrives in your Kindle library. A file copied over USB has to be in a native format such as unprotected MOBI, which is what this page makes.

Can I email the MOBI file to my Kindle?

No. Your Kindle's email address is part of Send to Kindle, and its list of formats has PDF, DOC, DOCX, TXT, RTF, HTML, images and EPUB, but no MOBI. Send the ePub itself instead: up to 50 MB by email or up to 200 MB through Send to Kindle on the web. Keep the MOBI for copying over USB.

How do I put the MOBI file on my Kindle?

Connect the Kindle to your computer with a USB cable. On Windows it shows up in File Explorer as Kindle; copy the .mobi into its Documents folder. On a Mac, Amazon says Kindle Scribe and Kindle models released in 2024 need its Send to Kindle app for Mac, which has a USB File Manager; earlier models need no extra app. Then tap Disconnect on the Kindle screen or unplug the cable.

Will the table of contents and cover survive?

Yes. Calibre builds the MOBI's table of contents from the ePub's own and adds a contents page at the start of the book unless the ePub already has one. The cover named in the ePub becomes the MOBI cover; Keep cover is on by default.

What happens to books protected with DRM?

They are refused before the conversion starts, and no workaround is offered: the same rule applies to every protected file on the site.

How long does the file stay on the server?

The uploaded ePub is deleted as soon as the job finishes. The converted MOBI stays downloadable for one hour and is wiped from the server within about two hours, whether or not you download it.

Guides

Getting an E-Book onto an Older Kindle That Won't Read ePubePub is the standard e-book format almost everywhere, except on the Kindle device itself, which has never read it natively.

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