Short answer: Amazon has already phased out MOBI in its major publishing and personal-document workflows. Reflowable MOBI uploads stopped being accepted by Kindle Direct Publishing (KDP) on August 1, 2021, fixed-layout MOBI uploads followed on March 18, 2025, and Amazon’s current Send to Kindle list includes EPUB but not MOBI. That does not prove that every existing, unprotected MOBI file has stopped opening on every Kindle.
For new books, authors should use EPUB, DOCX, or KPF. For personal documents, EPUB sent through Amazon’s current Send to Kindle tools is generally the safest replacement.
What “Kindle dropping MOBI” actually means
“Kindle will soon drop support for MOBI” is directionally right but stale as a news headline. The change affects several different Amazon systems, and they do not have identical rules.
| System | Current position | What it means |
|---|---|---|
| KDP reflowable ebooks | MOBI support ended August 1, 2021 | New and revised flowing-text books need another source format. |
| KDP fixed-layout ebooks | MOBI support ended March 18, 2025 | EPUB or KPF is the normal replacement; certain Japan-only horizontal episodic manga workflows have image-based provisions. |
| Send to Kindle | Amazon’s current list includes EPUB, PDF, DOC, DOCX, TXT, RTF, HTML and image formats, but not MOBI, AZW or PRC | Use EPUB or another listed format for new personal-document transfers. |
| Files already on a Kindle | Device- and file-dependent | Some locally copied, unprotected MOBI files may still open, but future compatibility and Amazon services are not guaranteed. |
Amazon’s current transfer documentation is available at Connect, Browse, and Transfer Files on E-Reader. Its KDP policy is documented in the MOBI Support for eBooks FAQ.
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The timeline
- August 1, 2021: Amazon ended MOBI support for reflowable KDP books.
- 2022–2023: Amazon announced and phased down MOBI handling for Send to Kindle personal documents. Historical customer notices should not be confused with a current universal device ban.
- March 18, 2025: Amazon ended MOBI support for fixed-layout KDP ebooks.
- August 16, 2026: Amazon’s current Send to Kindle documentation lists EPUB and other modern inputs, but not MOBI.
What changes for authors
Reflowable books
Novels, essays and most text-heavy books should be submitted as EPUB, DOCX or KPF. Amazon lists these formats in its Supported eBook Manuscript Formats guidance. EPUB is the most portable option when correctly structured and validated. DOCX is convenient for uncomplicated manuscripts. KPF, produced by Kindle Create, fits an Amazon-centered workflow.
Fixed-layout books
Image-led books, comics, children’s books and textbooks can require fixed positioning. Use EPUB or KPF and inspect the result carefully on relevant screen sizes. Amazon’s MOBI FAQ describes the supported alternatives and limited image-based provisions for specified Japan-only horizontal episodic manga workflows.
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- Light and compact - With adjustable brightness, high contrast ratio, and fast page turns.
- Effortless reading in any light - Read comfortably with a 6“ glare-free display, adjustable front light—now 25% brighter at max setting—and dark mode.
- Escape into your books - Tune out messages, emails, and social media with a distraction-free reading experience.
- Read for a while - Get up to 6 weeks of battery life on a single charge.
- Take your library with you - 16 GB storage holds thousands of books.
Source format versus delivery format
Uploading EPUB, DOCX or KPF does not mean customers receive that exact file. Amazon processes the source into a delivery file suited to the reading device or app. That processing is why a modern source format matters more than preserving an old MOBI export.
Author checklist
- Keep the editable manuscript, layout project or original EPUB.
- Export a standards-compliant EPUB, DOCX or KPF; do not create a new MOBI.
- Open the file in the free Kindle Previewer.
- Check the cover, table of contents, chapter navigation, font resizing, images, tables, links, footnotes, page breaks and special characters. For multilingual or right-to-left content, check those scripts specifically.
- Upload the validated source to KDP and retain EPUB as an archival master.
What changes for Kindle owners
Sending a new personal document
Amazon currently allows files up to 200 MB each through its supported transfer routes. EPUB is usually the best choice for a book or long-form document. PDF preserves page geometry but does not reflow well; DOCX and HTML are useful when Amazon should perform the conversion. Start at Send to Kindle, or use the Kindle apps, desktop applications or an approved personal Send to Kindle email address.
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- Battery life for your longest novel – A single charge via USB-C lasts up to 12 weeks.
- Read in any light – Adjust the display from white to amber to read in bright sunlight or in the dark.
- Confirm the EPUB is readable and not password-protected.
- Upload or attach it through Send to Kindle.
- Enable the option to add it to your Kindle library if cloud access across devices is required.
- Wait for processing and synchronization.
- Open it on the intended Kindle and inspect navigation, cover, images, footnotes and unusual characters.
Existing library documents
The KDP policy change does not automatically delete previously published books. Amazon says the publishing change applies to new uploads and revisions. A previous Amazon support notice, reproduced in an Amazon Customer Forum discussion, also said existing MOBI documents in a user’s library were not affected by the Send to Kindle change. Because that notice is historical, treat it as context rather than a new 2026 guarantee.
USB sideloading
Some Kindle models and software versions may still recognize an unprotected MOBI copied directly by USB. That is local device compatibility, not Amazon service support. USB copying may lack cloud synchronization, Amazon conversion, consistent metadata, thumbnails, annotations or newer typesetting features, and future firmware could change the result.
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- Our fastest Kindle Paperwhite ever – The next-generation 7“ Paperwhite display has a higher contrast ratio and 25% faster page turns.
- Ready for travel – The ultra-thin design has a larger glare-free screen so pages stay sharp no matter where you are.
- Escape into your books – Your Kindle doesn’t have social media, notifications, or other distracting apps.
- Battery life for your longest novel – A single charge via USB-C lasts up to 12 weeks.
- Read in any light – Adjust the display from white to amber to read in bright sunlight or in the dark.
Purchased and DRM-protected books
Commercial Kindle books are not ordinarily delivered to customers as ordinary MOBI files, and the KDP change does not mean purchased titles are automatically removed. For DRM-protected material, contact the original retailer or publisher for a supported format. Do not attempt to bypass DRM.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How to migrate a MOBI file
Best option: obtain the original source
- Ask the publisher, author, library or ebook service for an EPUB version.
- Send that EPUB through Send to Kindle.
- Open it on the target device.
- Check the cover, table of contents, images, footnotes and special characters.
Converting the original EPUB, DOCX or HTML is safer than repeatedly converting a file that has already passed through another ebook conversion.
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- Our fastest Kindle Paperwhite ever – The next-generation 7“ Paperwhite display has a higher contrast ratio and 25% faster page turns.
- Upgrade your reading experience – The Signature Edition features an auto-adjusting front light, wireless charging, and 32 GB storage.
- Ready for travel – The ultra-thin design has a larger glare-free screen so pages stay sharp no matter where you are.
- Escape into your books – Your Kindle doesn’t have social media, notifications, or other distracting apps.
- Adapts to your surroundings – The auto-adjusting front light lets you read in the brightest sunlight or late into the night.
If MOBI is the only file
A reputable ebook-management or conversion application can create an EPUB, but validate the result before transfer. Calibre is a commonly used free, open-source option; Amazon does not endorse every third-party converter. For author workflows, Kindle Previewer and Kindle Create are official free tools.
Common conversion problems
- Renaming .mobi to .epub: changing the extension does not change the internal container or metadata.
- Broken layout: obsolete CSS, unsuitable image dimensions, missing fonts or a damaged table of contents can be introduced during conversion.
- Successful upload, poor rendering: acceptance only proves that processing completed; it does not prove that every device view is correct.
- DRM restrictions: protected files may not be convertible or transferable through ordinary tools. Return to the source provider.
Choosing EPUB, DOCX, KPF or PDF
| Format | Best use | Strengths | Main risks |
|---|---|---|---|
| EPUB | Structured ebooks, custom typography, portable archives | Portable, flexible and suitable for reflowable content | Invalid structure, CSS, navigation, font, image and accessibility problems if poorly prepared |
| DOCX | Plain novels, essays and straightforward manuscripts | Easy for Word-based workflows | Complex layouts, manual spacing, tables and footnotes may convert unpredictably |
| KPF | Amazon-oriented authoring through Kindle Create | Integrated formatting and preview workflow | Less convenient as a general-purpose distribution file |
| Documents where exact page appearance matters | Preserves page geometry | Limited font resizing and reflow on small screens |
Amazon’s broader guidance on reflowable and fixed-layout content is in Paths to Getting Your Content on Kindle. Reflowable is generally preferable when accessibility, adjustable text and broad compatibility matter.
What not to assume
- A MOBI file opening over USB does not mean KDP or Send to Kindle still accepts MOBI.
- EPUB is an accepted Amazon input; that does not mean every Kindle treats an uploaded EPUB exactly like a standalone open-EPUB reader.
- AZW, AZW3 and MOBI should not be treated as interchangeable names for one identical file type.
- Every old MOBI book does not need to be re-uploaded or converted.
- Kindle Previewer is a validation aid, not a promise that every personal-document delivery will look identical on every customer device.
Bottom line for 2026
Stop creating new MOBI files. Authors should submit validated EPUB, DOCX or KPF files, while personal-document users should generally send EPUB through Amazon’s supported Send to Kindle pipeline. Existing unprotected MOBI files may continue to open locally, but EPUB is the more reliable, future-facing format for new transfers and publishing.
Quick Recap
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