Bulk Convert M4B to MP3 Online — Universal Compatibility

Convert M4B audiobooks to MP3 with automatic chapter splitting for playback on any device.

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

Drop M4B Files Here

100 MB or 2 hours per file Up to 50 files 3 parallel conversions 1 credit per 5 minutes

Encrypted EU Servers Auto-delete 1h

⚡ Median M4B → MP3 time (last 10k jobs): 274ms per minute

Chapters: Split into separate files

How it works

1 · Drop your files
Drag & drop or choose M4B files. No account required—paid plans unlock bigger batches, higher limits, and priority queues.
2 · We convert securely
Processed on our dedicated servers. Encrypted in transit & at rest. We never store filenames—only file types & sizes for accounting.
3 · Download & auto-delete
Grab your MP3 files in seconds. Files delete automatically after 1 hour. Delete anytime after downloading with one click.

About M4B →

M4B is Apple's audiobook format, essentially an M4A file with chapter markers and bookmark support. Introduced with iTunes in 2003, M4B uses AAC audio encoding in an MPEG-4 container—the same codec as M4A—but with additional metadata for chapter navigation and resume-position bookmarks. This makes M4B ideal for long-form audio content like audiobooks and podcasts. Files from Audible (after DRM removal), iTunes Store, and Librivox commonly use M4B format.

Learn more: M4B on Wikipedia

M4B supports sample rates up to 96 kHz and multi-channel audio, though most audiobooks use mono or stereo at 44.1 kHz for efficiency. The chapter markers embedded in M4B files enable navigation to specific sections—a feature lost when converting to formats like MP3 or WAV. For maximum compatibility with car stereos, older MP3 players, and non-Apple devices, converting M4B to MP3 is often necessary. For archival or editing, WAV extraction provides lossless quality.

About MP3 →

MP3 (MPEG-1 Audio Layer III) revolutionized digital audio when it was standardized in 1993 by the Fraunhofer Society. Using psychoacoustic compression, MP3 removes audio frequencies that humans typically cannot perceive, achieving 10:1 compression or better while maintaining excellent subjective quality. MP3 supports sample rates from 8-48 kHz and 16-bit audio. At 256 kbps, most listeners cannot distinguish MP3 from the original source in blind tests.

Learn more: MP3 on Wikipedia

MP3 remains the most universally compatible audio format, supported by every music player, smartphone, computer, and web browser. While newer codecs like AAC and Opus offer marginally better compression efficiency, MP3's ubiquitous support makes it the safest choice for sharing audio. The format's patents expired in 2017, making it completely free to use without licensing concerns.

Frequently Asked Questions

What is the difference between M4B and MP3?

M4B is Apple's audiobook format with chapter markers and bookmark support—designed for iTunes and Apple Books. MP3 is a universal audio format without built-in chapter support but works on virtually every device. MP3 provides maximum compatibility, while M4B is optimized for audiobook playback. Have standalone AAC files instead? Try AAC to MP3.

Will converting M4B to MP3 preserve chapter structure?

Yes! We split by chapter by default. Each chapter in your M4B audiobook becomes a separate MP3 file, perfect for players that don't support M4B chapters natively. Files are named with chapter numbers and titles (e.g., my-audiobook-chapter-01-introduction.mp3). Prefer a single combined file? Toggle off "Split by chapter" in the options panel below the dropzone.

Why would I convert M4B audiobooks to MP3?

Universal compatibility and DRM-free playback. MP3 works on every audio player, car stereo, and non-Apple device. If you have DRM-free M4B files from sources like Libro.fm or personal recordings and want them to play on Android, Kindle, or older devices, converting to MP3 ensures compatibility.

What MP3 settings do you use for audiobooks?

We encode at 320 kbps MP3 (maximum quality) using the high-quality LAME encoder. This provides excellent clarity for spoken word content while maintaining compatibility with all MP3 players. The output uses constant bitrate (CBR) for reliable playback and scrubbing.

Can I convert DRM-protected Audible M4B files?

No. This converter only works with DRM-free M4B files. Audible audiobooks purchased from Amazon are encrypted with DRM and cannot be converted directly. You must use Audible's official apps or remove DRM first (which may violate Audible's terms of service).

What happens to metadata and album art?

Yes, they transfer. Text metadata (title, author, narrator, genre) and cover art transfer automatically. M4B tags are automatically mapped to ID3 tags during conversion. Only chapter markers are lost.

How long can my audiobook files be?

Duration limits depend on your plan: Guest/Free: 120 minutes, Pro: 3000 minutes (50 hours). This accommodates everything from short stories to full-length audiobooks and podcast archives.

What are the limits for this converter?

Tier	Max File Size	Max Files/Batch	Parallel Processing
Guest/Free	100 MB	50 files	3 at once
Pro	2048 MB	1000 files	6 at once

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

How are credits calculated for this conversion?

Cost: 1 credit per 5 minutes

How it works:

Files up to 5 minutes: 1 credit
6-10 minutes: 2 credits
11-15 minutes: 3 credits
16-20 minutes: 4 credits

Example: A 10-minute file = 2 credits. A 180-minute (3h) audiobook = 36 credits.

Why per-minute? Audio conversion time scales with content duration, not file size. Longer audio requires proportionally more processing.

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 5 minutes, audiobook files under 5 MB cost 1 credit each. Pro users can convert 12,000 audiobook files per month.

Answers at a Glance

Quick answers to common questions.

What's New in M4B to MP3

Latest improvements to this converter

Last updated December 16, 2025

Dec 16, 2025

Initial release of M4B to MP3 converter with high-quality LAME encoding for audiobook conversion.

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

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

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