Free Online MOBI to AZW3 Converter

Convert MOBI to AZW3 online for free.

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MOBI vs AZW3: Side-by-side

Technical comparison of the two formats — useful for deciding which to use, or for confirming what changes during conversion.

Property	MOBI	AZW3
Full name	Mobipocket eBook	Kindle Format 8
Year introduced	2000	2011
Developer / standard body	Mobipocket / Amazon	Amazon
MIME type	application/x-mobipocket-ebook	application/vnd.amazon.ebook
File extension	.mobi	.azw3
Compression	PalmDOC compression	Variable
Color / data depth	N/A	N/A
Max dimensions / size	Software-limited	Software-limited
Transparency	No	No
Animation	No	No
Standard / specification	Mobipocket	Amazon
Best for	Older Kindle devices (replaced by AZW3 then KFX)	Modern Kindle devices — enhanced typography and layout

About the MOBI Format

MOBI is an ebook format originally developed by Mobipocket SA and later acquired by Amazon in 2005 for use on Kindle devices. Based on the Open eBook standard with proprietary extensions, MOBI supports reflowable content, bookmarks, annotations, and basic formatting including images, tables, and text styles. It became the primary format for personal documents and sideloaded content on Kindle eReaders, working on every Kindle model ever produced.

Amazon has since deprecated MOBI in favor of the more capable AZW3 (KF8) and KFX formats, which support enhanced typesetting, embedded fonts, and responsive layouts. As of 2022, Amazon's Send to Kindle service no longer accepts MOBI files for email delivery. However, MOBI remains widely used for legacy Kindle compatibility and is still supported by many third-party reading apps. Converting MOBI to EPUB allows reading on non-Kindle devices, while converting to AZW3 provides a modern Kindle reading experience.

MOBI to AZW3 FAQ

Quick answers about compatibility, quality, metadata handling, and the most common reasons to convert MOBI files to AZW3.

Can I convert MOBI books to AZW3 for my Kindle or Kobo?

Yes. Upload your MOBI ebook and iFormat converts it to AZW3 with chapter structure, cover art, and formatting preserved. Load the AZW3 onto your Kindle, Kobo, Nook, or any eReader that supports the format.

How to convert MOBI to AZW3 without losing the table of contents

Chapter navigation, the cover image, and text formatting all carry over during conversion. The AZW3 has proper chapter links so you can jump between sections on your eReader just like the original MOBI.

Can I convert multiple MOBI ebooks to AZW3 at once?

Yes — upload a batch of MOBI files and iFormat converts them all to AZW3. Each book downloads separately or as a ZIP, so you can convert an entire library in one session.

Does the text still reflow after converting to AZW3?

Yes — AZW3 keeps text reflowable, so it adapts to any screen size and font setting on your eReader rather than being locked to a fixed page like a PDF.

Which reader is AZW3 for?

AZW3 is the AZW3 format best for its intended use. Convert your MOBI to AZW3 when your eReader or app opens AZW3 more reliably, so the whole library works on one device.

Is there a file size limit for MOBI to AZW3 conversion?

The free plan supports files up to 50 MB, which covers the large majority of MOBI files. For longer or higher-resolution files, Starter raises the limit to 100 MB, Plus to 1 GB, and Pro to 5 GB.