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MOBI is now a legacy format. It is not included in Amazon’s current wireless Send to Kindle supported-format list, so do not rely on being able to upload a MOBI file directly. If your MOBI file is rejected, obtain an EPUB or PDF version, or convert it with a reputable tool when you have the legal right to do so.
Which file format should you use?
| File type | Current recommendation | Best use |
|---|---|---|
| EPUB | Recommended for most ebooks | Reflowable reading with adjustable text size |
| Supported by Send to Kindle | Manuals, forms, worksheets, scans, and documents where page layout matters | |
| MOBI | Legacy format; do not rely on current wireless support | Convert or replace with EPUB or PDF when possible |
Amazon’s current Send to Kindle documentation lists EPUB and PDF among its supported document formats. The same current wireless list does not include MOBI. Amazon’s Kindle publishing guidance has also moved away from MOBI and recommends EPUB, DOCX, or KPF for current ebook production.
Choose an EPUB when you want a normal ebook experience: adjustable font size, more natural text wrapping, and better adaptation to different Kindle screens. Choose a PDF when the document’s pages, diagrams, forms, or precise visual arrangement are more important than flexible text.
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A Kindle e-reader or the free Kindle app is all you need for the reading side of this process. You do not need a special Kindle model to use Send to Kindle, although device-specific USB requirements can vary.
Method 1: Add an EPUB or PDF through Send to Kindle
The website is usually the most device-neutral option and is the best place to start if the file is on a Windows PC or Mac.
- Open Amazon’s Send to Kindle service in a web browser.
- Sign in with the Amazon account connected to your Kindle or Kindle app.
- Choose the file-upload option and select your EPUB or PDF file.
- When Amazon displays the available destinations, select the Kindle device or Kindle app you want to use. Depending on the workflow, you may also send the document to your Kindle library.
- Submit the file and wait for Amazon to process it.
- On the Kindle, connect to Wi-Fi or cellular service if supported, open the library, and synchronize or refresh it.
Amazon documents a maximum file size of 200 MB per file for the documented e-reader transfer workflow. Very large PDFs may still take time to process or download, especially over a slow connection.
If the book does not appear immediately
Check that the Kindle is online, that you used the correct Amazon account, and that you selected the intended device or library destination. Refresh the library and check the appropriate filter; a personal document may not appear in exactly the same view as books purchased from the Kindle Store.
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Method 2: Use Send to Kindle for Windows or Mac
Amazon also provides official Send to Kindle desktop applications. This is convenient when you regularly transfer documents from a computer.
- Install Amazon’s official Send to Kindle desktop application.
- Sign in with the Amazon account associated with your Kindle library.
- Drag the EPUB or PDF into the application, or use its file-selection control.
- Choose the target Kindle device or library destination.
- Send the document and allow time for it to synchronize.
The available controls and labels can change as Amazon updates the application. The important points are to use the official application, sign in to the correct account, and select the correct destination before sending.
For Mac users, Amazon’s current transfer documentation gives special guidance for USB transfers involving Kindle Scribe and Kindle devices released in 2024. It also describes computer and operating-system requirements for its USB Manager feature. These requirements do not mean that every Kindle owner needs a Scribe or a separate USB workflow; they matter when you are transferring files by cable to a newer device.
Method 3: Email the file to your Kindle
Every compatible Kindle device and Kindle app has its own Send to Kindle email address. This method is useful when the file is already attached to an email or stored on a computer without the Send to Kindle website being convenient.
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- Find the target device’s Send to Kindle email address in your Amazon account’s device or content settings, or in the Kindle’s account settings.
- In Amazon’s personal-document settings, add the email address you will use as an approved sender.
- Create a new email from that approved address.
- Attach the EPUB or PDF file. Do not rename a MOBI file to make it look like an EPUB; changing the extension does not convert the file.
- Send the message to the Kindle’s unique Send to Kindle address.
- Connect the Kindle to the internet and check the library after processing and synchronization.
If email sending fails, check all three addresses and settings: the sender must be approved, the destination must be the current address for the intended Kindle, and the attachment must be an accepted format. For the current wireless workflow, use EPUB or PDF rather than MOBI.
Privacy reminder: Send only documents you own or are authorized to use. Avoid emailing confidential medical, financial, work, or identity documents unless you understand the privacy implications of sending them through an online document-delivery service.
Method 4: Send a file from the Kindle app on iPhone, iPad, or Android
Amazon’s help documentation supports uploading documents through the Kindle app for iOS and Android. The exact button name may differ by app version, so look for the app’s document-sharing or Send to Kindle function rather than relying on one permanent label.
- Save the EPUB or PDF to the Files app, cloud storage, downloads folder, or another location that your phone or tablet can access.
- Open the Kindle app and locate its document-sharing or Send to Kindle function.
- Select the EPUB or PDF from the device’s file picker or share sheet.
- Choose the Kindle library or available destination when prompted.
- Leave the Kindle app and target device connected to the internet while the document synchronizes.
If the file does not appear, confirm that it was sent from the correct Amazon account and check both the Kindle app and the library associated with the account. App layouts vary between iOS, Android, and different releases.
Method 5: Transfer a file by USB
USB transfer can be useful when wireless delivery is unavailable or when you want to copy a file directly from a computer. However, USB behavior is not identical across every Kindle generation. Amazon currently recommends wireless Send to Kindle and provides device-specific instructions for newer models and Mac computers.
- Connect the Kindle to the computer with a USB data cable, not a charge-only cable.
- Wake or unlock the Kindle if necessary and wait for the computer to recognize it.
- Open the Kindle’s storage and locate the document area if the device exposes it.
- Copy the compatible file according to the device’s current transfer behavior.
- Safely eject the Kindle before disconnecting the cable.
- Open the Kindle library and look for the document.
A cable that charges the Kindle may not support data transfer. Newer Kindle devices, including Kindle Scribe and Kindle models released in 2024, can have additional Mac and USB Manager requirements documented by Amazon. If the Kindle does not appear on the computer, try a different data cable, USB port, or supported computer workflow before assuming that the ebook file is defective.
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How EPUB behaves on Kindle
EPUB is the preferred current route for a normal, reflowable ebook. Send to Kindle processes the EPUB for delivery to the Kindle ecosystem, allowing the content to adapt more naturally to screen size and text settings than a fixed page does.
That does not guarantee perfect formatting. A heavily designed, malformed, poorly structured, or encrypted EPUB may display incorrectly or fail processing. If you created the EPUB yourself, use a standards-compliant file and validate it. For books prepared for publication, Amazon recommends checking the content with Kindle Previewer.
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Encryption and access restrictions can also prevent processing. Remove protection only when you are legally permitted to do so; do not attempt to bypass DRM on material you are not authorized to alter.
How PDF behaves on Kindle
PDF is useful when the original page is the thing you need to preserve. It is a practical choice for:
- Instruction manuals and technical documents
- Forms and worksheets
- Scanned material
- Documents containing charts, diagrams, or precise page layouts
- Study material where page references must remain stable
The trade-off is readability. A PDF generally keeps its fixed page layout, so a full-size page may be difficult to read on a smaller Kindle screen. Pinching, zooming, or rotating the device may be necessary. Amazon warns that PDFs containing embedded formatting or images may not convert well if a conversion process is used, so do not assume that every PDF will become a comfortable reflowable ebook.
If a PDF is hard to read, look for a legitimate EPUB edition of the same work. An EPUB may provide a better reading experience, but it will not necessarily preserve the original PDF’s page design.
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What to do with a MOBI file
MOBI appears in many older Kindle tutorials because it was once a common Kindle ebook format. Current guidance is different: Amazon’s present Send to Kindle wireless format list does not list MOBI, and Amazon’s KDP documentation says support for MOBI uploads for fixed-layout ebooks ended on March 18, 2025. Amazon recommends EPUB, DOCX, or KPF for current ebook production.
If you already have a MOBI file:
- Look for an EPUB or PDF version first. This is usually the cleanest option.
- Do not change the filename extension. Renaming
book.mobitobook.epubdoes not convert its internal format. - Use a reputable ebook-conversion tool only when permitted. Respect copyright, licensing terms, and DRM restrictions.
- Validate the resulting EPUB if formatting matters, especially if you created or converted the book yourself.
- Do not assume USB will solve the problem. An old MOBI file may work differently across Kindle generations, and current wireless documentation does not promise MOBI support.
If Send to Kindle rejects the MOBI, treat that as consistent with the current supported-format guidance rather than repeatedly retrying the same file.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Troubleshooting checklist
The document does not appear
- Confirm that the Kindle is connected to Wi-Fi or cellular service where supported.
- Check that the website, app, or email used the correct Amazon account.
- Confirm that you sent the file to the intended device or library.
- Refresh or synchronize the Kindle library.
- Check document or library filters rather than looking only in purchased books.
- Allow time for a large file or complex document to process.
Email delivery fails
- Make sure the sender’s email address is on Amazon’s approved personal-document list.
- Verify the target Kindle’s current Send to Kindle email address.
- Use EPUB or PDF for the current wireless workflow.
- Check the attachment size and make sure the file is actually attached.
- Do not disguise a MOBI by changing its extension.
The PDF is transferred but difficult to read
This may be a limitation of the PDF’s fixed layout, not a transfer failure. Try landscape orientation or zooming, or obtain a lawful EPUB edition if you want adjustable text. Amazon cannot perfectly reformat every complex PDF, particularly one containing intricate formatting, images, or scanned pages.
The EPUB has formatting problems
- Try a standards-compliant EPUB from a reliable source.
- Remove password protection or encryption only when legally allowed.
- Check the EPUB with an appropriate validator.
- If you are preparing a publication, preview it with Kindle Previewer before sending or publishing.
- Look for missing fonts, broken navigation, oversized images, or unusual fixed-layout elements.
The MOBI file is rejected
Do not treat rejection as proof that your Kindle is broken. MOBI is a legacy format and is not included in Amazon’s current wireless supported-format list. Obtain an EPUB or PDF copy, or use a lawful conversion workflow.
Copyright, DRM, and personal documents
Transfer only files you own or are authorized to read. A file being technically transferable does not give you permission to copy or distribute it.
DRM is a separate issue from the Kindle’s ability to receive a file. Amazon distinguishes DRM-protected and DRM-free purchased Kindle books. According to Amazon’s DRM documentation, verified purchasers can download EPUB or PDF files for confirmed DRM-free books beginning January 20, 2026; borrowed books are excluded. That option depends on the book’s DRM status and purchase verification, not simply on owning a Kindle.
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In practical terms, if an Amazon-purchased book does not offer an authorized EPUB or PDF download, do not assume that you can extract, convert, or send it elsewhere. Use the options Amazon and the rights holder provide.
Frequently Asked Questions
Can I send an EPUB directly to my Kindle?
Yes. EPUB is included in Amazon’s current Send to Kindle workflow. You can upload it through the website or desktop app, send it from the Kindle app on iOS or Android, or email it from an approved address.
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Can I still send MOBI files to a Kindle?
MOBI is a legacy format and is not included in Amazon’s current wireless Send to Kindle supported-format list. If the file is rejected, obtain an EPUB or PDF version or convert it lawfully with a reputable ebook tool. Renaming the file extension will not convert it.
Should I use EPUB or PDF for Kindle?
Use EPUB for most ordinary ebooks because it can reflow and resize. Use PDF when preserving the original page layout is more important, such as with forms, manuals, scans, and worksheets.
Why is my PDF hard to read on my Kindle?
A PDF normally preserves a fixed page layout, which can make a full-size page awkward on a small screen. Try landscape mode or zooming, or obtain a legitimate EPUB version if adjustable text would be more useful.
Why is my emailed Kindle document not appearing?
Check that the sender’s address is approved in Amazon’s personal-document settings, that you used the target device’s current Send to Kindle address, that the attachment is EPUB or PDF, and that the Kindle is connected to the internet.
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For the current Kindle workflow, send EPUB for reflowable ebooks and PDF for fixed-layout documents. Use Send to Kindle through Amazon’s website, desktop app, mobile app, or approved email address. Treat MOBI as legacy: do not rely on wireless support, do not rename its extension, and use a lawful EPUB/PDF alternative or conversion when necessary.
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