Convert EPUB to AZW3 Online — For Best Kindle Typography

Custom fonts, advanced layouts, and CSS3 styling on modern Kindles.

Drop up to 50 EPUBs at once — no install, no sign-up required.

Drop EPUB Files Here

50 MB per file Up to 50 files 3 parallel conversions 1 credit per 10 MB

Encrypted EU Servers Auto-delete 1h

⚡ Median EPUB to AZW3 time (last 10k jobs): 355ms

How it works

1 · Drop your files
Drag & drop or choose EPUB files. No account required—paid plans unlock bigger batches, higher limits, and priority queues.
2 · We convert securely
Processed on our dedicated servers using Calibre. Encrypted in transit & at rest. We never store filenames—only file types & sizes for accounting.
3 · Download & auto-delete
Grab your AZW3 files in seconds. Files delete automatically after 1 hour. Delete anytime after downloading with one click.

About EPUB →

EPUB (Electronic Publication) is an open ebook standard developed by the International Digital Publishing Forum (IDPF), now part of the W3C. First released in 2007 as a successor to Open eBook, EPUB has become the most widely supported ebook format. EPUB files are ZIP archives containing HTML/XHTML content, CSS styling, images, and metadata organized according to the EPUB specification.

Learn more: EPUB on Wikipedia

EPUB's key feature is reflowable content—text automatically adapts to different screen sizes, making it ideal for e-readers, tablets, and phones. The format supports embedded fonts, multimedia (in EPUB 3), and accessibility features. Most e-readers except Amazon Kindle natively support EPUB.

About AZW3 →

AZW3, also known as KF8 (Kindle Format 8), is Amazon's modern ebook format introduced in 2011 with the Kindle Fire. AZW3 files use the .azw3 extension and support HTML5, CSS3, and advanced typography features not available in the older MOBI format.

Learn more: KF8/AZW3 on MobileRead Wiki

AZW3 offers superior formatting capabilities compared to MOBI, including custom fonts, embedded audio/video, SVG graphics, and complex layouts. It's the recommended format for modern Kindle devices (2012 and later), though older Kindles require the MOBI format.

Frequently Asked Questions

What is AZW3 format?

AZW3 (Kindle Format 8 / KF8) is Amazon's modern ebook format introduced in 2011. It supports HTML5, CSS3, custom fonts, embedded media, and advanced typography—offering significantly better formatting than the older MOBI format.

Why convert EPUB to AZW3 instead of MOBI?

Better formatting. AZW3 preserves complex layouts, custom fonts, and advanced styling that MOBI cannot handle. For modern Kindles (2012+), AZW3 is the recommended format. Use MOBI only for older Kindle devices.

What devices support AZW3?

AZW3 is supported by all Kindle devices from 2012 onwards, including Kindle Paperwhite (all generations), Kindle Voyage, Kindle Oasis, and Kindle Fire tablets. It also works with Kindle apps on iOS, Android, PC, and Mac.

Can I convert DRM-protected EPUBs?

No. DRM-protected EPUB files (purchased from stores with copy protection) cannot be converted. You must remove DRM protection first using appropriate tools, or contact the publisher for a DRM-free version.

Will formatting be preserved?

Yes, AZW3 preserves excellent formatting including custom fonts, complex layouts, images, and CSS styling. Calibre handles the conversion process to maintain the highest fidelity possible from your source EPUB.

Can I sideload AZW3 files to my Kindle?

Yes! You can transfer AZW3 files via USB cable or use Amazon's Send to Kindle service. Connect your Kindle, copy the .azw3 file to the 'documents' folder, and it will appear in your library.

How does AZW3 compare to Amazon's native Kindle format?

AZW3 is Amazon's native format. When you buy a Kindle book, Amazon delivers it as AZW3 (also called KF8). The only difference is that purchased books have DRM encryption, while converted AZW3 files don't. The underlying format, features, and rendering are identical.

Can I use Send to Kindle with AZW3 files?

Not directly. Amazon's Send to Kindle service doesn't accept AZW3 uploads—it prefers EPUB, PDF, or DOCX. However, USB sideloading preserves the full quality of your AZW3 files with no re-conversion. Connect via USB and copy to the documents folder.

Why does my Kindle show AZW3 files as 'documents'?

Sideloaded books appear under Downloaded or All Items, separate from Amazon purchases. This is a Kindle limitation, not a format issue. To organize better, use Calibre with the Kindle plugin to sync metadata and covers, making sideloaded books look like purchased ones.

What are the limits for this converter?

Tier	Max File Size	Max Files/Batch	Parallel Processing
Guest/Free	50 MB	50 files	3 at once
Pro	1024 MB	1000 files	6 at once

Note: File size limits are specific to this converter. Batch and parallel processing limits apply to all ebooks converters site-wide. See all converter limits →

How are credits calculated for this conversion?

Cost: 1 credit per 10 MB

How it works:

Files up to 10 MB: 1 credit
11-20 MB: 2 credits
21-30 MB: 3 credits
31-40 MB: 4 credits

Example: A 5 MB file = 1 credit. A 95 MB file = 10 credits.

Why per-megabyte? Larger files require more resources (processing, bandwidth, storage).

What are my daily and monthly credit limits?

Credit allocations vary by account tier:

Tier	Daily Limit	Monthly Limit
Guest	100 credits/day	—
Free	100 credits/day	—
Pro	—	12,000 credits/month

Daily credits (Guest & Free tiers) reset every day at midnight UTC. Monthly credits (Pro) reset on your billing cycle date.

Note: With 1 credit per 10 MB, images under 10 MB cost 1 credit each. Pro users can convert 12,000 images per month.

Answers at a Glance

Quick answers to common questions.

Related Ebook Converters

Need a different format? Try these alternatives.

EPUB MOBI

For older Kindle devices (pre-2012)

EPUB KEPUB

40-80x faster rendering on Kobo devices

What's New in EPUB to AZW3

Latest improvements to this converter

Last updated January 19, 2026

Jan 19, 2026

Initial release of EPUB to AZW3 converter for modern Kindle devices.

Need to get more done? Pro starts from $5.

1 GB files 1,000 per batch Priority queue Web + API

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