MOBI is the older Kindle format, superseded by AZW3 and retired by Amazon for new sideloaded books.
Common Uses
Reading eBooks on Kindle
Mobile reading
eBook distribution
MOBI Conversion FAQ
What is a MOBI file?
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MOBI (Mobipocket) is an eBook format originally designed for Mobipocket Reader and Amazon Kindle devices.
Can I read a MOBI book on something that is not a Kindle?
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Only after converting it, in general. MOBI is Amazon's own format and support outside its apps and devices is patchy, so moving a book to a Kobo, an Apple device or a general-purpose reader means converting first. Store purchases are the exception that stops the whole process: if the file carries Amazon's DRM, no converter can open it, here or anywhere else. Amazon stopped accepting MOBI for new publishing in 2022, and the format cannot express modern CSS, embedded fonts or fixed layout.
Why do purchases arrive as MOBI?
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Because the format is the store's own delivery wrapper, tied to its apps and, for paid content, to your account. That is what makes it convenient inside that ecosystem and awkward outside it. Files that are not account-locked convert normally; protected ones cannot be opened by any converter, which is a deliberate property of the format rather than a limitation here. MOBI is the Mobipocket format Amazon bought in 2005 and used as the original Kindle format.
Why does my purchased MOBI refuse to convert?
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Because it is encrypted. A store-bought MOBI is locked to an account, and the file a converter sees is ciphertext rather than a book — there is nothing to read until the store's software decrypts it for its own reader. Removing that protection is a legal grey area in many countries and is not something this site does. Files you made yourself, or downloaded DRM-free, convert normally.
Does the table of contents survive converting a MOBI?
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Yes, wherever the target has somewhere to put it. Ebook formats store navigation as real structure — a list of chapter anchors that the reader turns into a jump menu — and that is carried between them. A fixed-layout export turns it into bookmarks instead, and a plain-text export loses it along with everything else structural. Chapter breaks themselves survive all three.
What if my MOBI is a scan rather than real text?
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Then nothing downstream can read it until OCR has run. A scanned page is a picture of words: it looks fine, and searching, copying or converting to an editable document all come back empty. Optical character recognition adds a real text layer over the image, after which the words are selectable and the conversion produces an actual document instead of a wrapper around a photograph.
Is the cover image kept when I convert a MOBI?
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It is, provided the book records one as the cover rather than merely having a picture on its first page. That distinction is why a converted book sometimes shows a blank placeholder in a library: the image is still inside the file, but nothing marks it as the cover, so the reader app displays nothing. It is metadata rather than content, and it can be set afterwards without touching the text.
Does a MOBI have fixed pages?
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No — content flows, and pages appear only when something decides on a page size. Change the font, the margins or the screen and the page numbering changes with it. That is why a page reference from a MOBI is unreliable, and why converting to a fixed-layout format is the step that makes page numbers mean something.
Should I still be saving new files as MOBI?
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Only if something downstream demands it. The format still opens, and there is no urgency about converting an archive that is not causing trouble, but it is no longer where the tooling or the efficiency is going. For anything new, a current format costs nothing extra and avoids the next round of this question a few years from now.
Is MOBI usable outside Amazon's ecosystem?
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Partly. The format itself is documented well enough that several readers and conversion tools handle it, so a DRM-free file moves around fine. Anything bought from the store is a different matter — it is encrypted against your account and cannot be opened by any third-party tool, which is the design working as intended rather than a fault.
Can I convert a whole folder of MOBI files in one go?
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With an account, yes — drop them in together and they are queued as one job rather than handled one at a time, with the same settings applied across the batch and the results returned together. Free conversions run a single file at a time (merge tools take two); a paid plan is what unlocks batch processing and the larger per-file limit, which is what makes converting a whole archive practical.
What happens to my MOBI file after the conversion?
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It is deleted. The upload and the converted result both sit on the server only as long as the job needs them and are then removed automatically; the transfer runs over HTTPS in both directions. Nobody reads the contents, nothing is indexed, and nothing is passed to anyone else. If you would rather not wait for the automatic sweep, closing the job removes the files immediately.
