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Repair Windows errors before they cause bigger problemsFix Now →Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Amazon lists EPUB, PDF, HTML, RTF, TXT and image files for its Send to Kindle service; separate Amazon transfer guidance also lists DOC and DOCX. Xteink’s official specifications for the X3 and X4 Pro list EPUB and TXT documents, with image and font formats varying by model. These are route- and model-specific claims: a file accepted by a service is not automatically a guarantee that every e-reader opens that file natively.
Format support at a glance
| Device or transfer route | Documents and ebooks | Other listed formats | What the specification means |
|---|---|---|---|
| Amazon Send to Kindle | EPUB, PDF, HTML/HTM, RTF, TXT | JPEG/JPG, GIF, PNG, BMP | These are file types accepted by Send to Kindle, not a universal native-reading list for every Kindle. Amazon says web uploads can be 200 MB or smaller. Amazon Send to Kindle |
| Amazon transfer guidance | EPUB, PDF, DOC/DOCX, HTML/HTM, RTF, TXT | PNG, GIF, JPG/JPEG, BMP | Amazon provides transfer and operating-system guidance; check the instructions for the specific Kindle model for USB details. Amazon transfer guidance |
| Xteink X3 | EPUB, TXT | JPG and BMP images; BIN fonts | The X3 product page says it is compatible with the official Xteink app only. Xteink X3 specifications |
| Xteink X4 Pro | EPUB, TXT | JPG and BMP images; BIN and XTF fonts | The product page describes imports through the app or USB. It identifies TTF font support as planned for a future firmware update, not current support. Xteink X4 Pro specifications |
What the Kindle format list does—and does not—tell you
Amazon’s Send to Kindle documentation describes a service for delivering files to a Kindle library and Kindle apps. It says the service accepts EPUB, PDF, HTML/HTM, RTF, TXT, and the listed image formats. Amazon’s separate transfer guidance includes DOC and DOCX as well. The route matters: these lists describe what Amazon says can be sent or transferred, not a promise that every Kindle model will open every listed file as an unchanged, native ebook file.
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For EPUB in particular, the precise statement is that Amazon accepts EPUB through Send to Kindle. That is different from saying that every Kindle natively reads a raw EPUB file copied directly to the device. If you plan to use USB or another route, follow the current instructions for your Kindle model rather than inferring compatibility from the Send to Kindle upload list.
What the Xteink X3 and X4 Pro support
Xteink X3
The official X3 product page lists EPUB and TXT as document formats, JPG and BMP for images, and BIN for fonts. It says the X3 is compatible with the official Xteink app only, so do not assume the X4 Pro’s USB-import option applies to the X3.
#1 Best Overall
- 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.
Xteink X4 Pro
The official X4 Pro page lists EPUB and TXT documents, JPG and BMP images, and BIN and XTF fonts. It describes importing books through either the Xteink app or USB. Although the page mentions TTF font support as planned for a future firmware update, it does not list TTF as currently supported.
These specifications apply to the named models, not automatically to every Xteink reader or firmware version. The current official pages for these two models do not list PDF, DOC, or DOCX as document formats.
Rank #2
- 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.
Choose the right route for your file
- For a Kindle: If sending through Amazon’s service, check the Send to Kindle accepted-file list and use the upload, email, app, or desktop route described there. The web uploader’s stated limit is 200 MB per upload.
- For an Xteink X3: Use EPUB or TXT for documents and the official Xteink app for compatibility described on its product page.
- For an Xteink X4 Pro: Use EPUB or TXT for documents; the product page describes app and USB import. Do not treat planned TTF support as available until the applicable firmware update is released.
- For another Xteink model: Check that model’s own official specification and its current firmware notes. The X3 and X4 Pro lists do not establish brand-wide compatibility.
Keep publishing formats separate from reader compatibility
Amazon’s Kindle Direct Publishing format page is for ebook manuscripts submitted for publication, not a consumer-device compatibility chart. It lists EPUB, KPF, DOC/DOCX, HTML, RTF, TXT, and PDF in that publishing context. It also says fixed-layout MOBI submissions would no longer be accepted effective March 2025. Those submission rules should not be used to infer which files a Kindle or Xteink device reads when you transfer personal documents. Amazon KDP manuscript file formats
Amazon’s Send to Kindle support page describes the service as allowing documents to be sent to a Kindle library and Kindle devices and apps at no additional cost. Because Amazon and Xteink can update their service and product specifications, consult the linked official page for the route or exact model you intend to use.
Quick Recap
Best Value
- 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.
Rank #4
- 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.
Rank #3
- 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.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
