Convert M4A to M4B

M4A to M4B converter that runs entirely in your browser. 100% free, no signup, no upload — your files never leave your device. One-click batch conversion.

Conversions

About formats

M4A

M4A is an audio-only MPEG-4 container, commonly used for audio tracks purchased from the iTunes Store. It typically wraps AAC or ALAC audio. M4A offers better quality than MP3 at similar bitrates and is natively supported by Apple devices and most modern media players.

Developer
Apple / ISO/IEC
Initial release
2001
Compression
Lossy or lossless
Color depth
up to 24-bit
Transparency
No
Animation
No

Best for

  • Playing iTunes Store audio
  • Apple ecosystem music storage
  • Audiobook and podcast delivery
  • High-quality portable audio
  • ALAC lossless audio storage

Pros

  • +Better quality than MP3 at similar bitrates
  • +Natively supported by Apple devices
  • +Can wrap lossless ALAC audio
  • +Multi-track MPEG-4 container

Cons

  • −Less universal than MP3 on non-Apple devices
  • −May carry FairPlay DRM
  • −Slightly more complex container
  • −Some players lack M4A support

M4B

M4B is an MPEG-4 audio container variant specifically designed for audiobooks. It is identical to M4A in structure but supports chapter markers and bookmarking so players can resume playback. M4B is commonly used by iTunes and Apple Books.

Developer
Apple
Initial release
2003
Compression
Lossy or lossless
Color depth
up to 24-bit
Transparency
No
Animation
No

Best for

  • Distributing audiobooks with chapters
  • iTunes and Apple Books audio
  • Bookmarkable spoken-word content
  • Long-form audio with navigation
  • Resumable podcast delivery

Pros

  • +Supports chapter markers and bookmarking
  • +Resumes playback across devices
  • +Identical audio quality to M4A
  • +Recognized by iTunes and Apple Books

Cons

  • −May carry FairPlay DRM
  • −Less universal than plain MP3
  • −Primarily Apple-ecosystem format
  • −Some players ignore chapter markers

How to convert M4A to M4B

  1. 1

    Select M4A files from your computer, Google Drive, Dropbox, a URL, or by dragging them onto the page.

  2. 2

    Choose m4b — or any other format you need as a result (more than 200 formats supported).

  3. 3

    Let the file convert, then download your m4b file right away.

M4A vs M4B

PropertyM4AM4B
CompressionLossy or losslessLossy or lossless
Color depthup to 24-bitup to 24-bit
Multi-trackYesYes
DRM supportYesYes
Open formatNoNo

When to use M4A vs M4B

M4A

  • Playing iTunes Store audio
  • Apple ecosystem music storage
  • Audiobook and podcast delivery
  • High-quality portable audio
  • ALAC lossless audio storage

M4B

  • Distributing audiobooks with chapters
  • iTunes and Apple Books audio
  • Bookmarkable spoken-word content
  • Long-form audio with navigation
  • Resumable podcast delivery

Use cases for M4A → M4B

  • Playing iTunes Store audio
  • Apple ecosystem music storage
  • Audiobook and podcast delivery
  • High-quality portable audio
  • ALAC lossless audio storage
  • Distributing audiobooks with chapters
  • iTunes and Apple Books audio
  • Bookmarkable spoken-word content
  • Long-form audio with navigation
  • Resumable podcast delivery

Frequently Asked Questions

Is converting M4A to M4B free?
Yes. This M4A → M4B converter runs entirely in your browser and is completely free — no account, no credits, no watermark.
Which devices and platforms can I use to convert M4A to M4B?
Any modern device with a current web browser: Windows, macOS, Linux, Android, iPhone and iPad. There is nothing to install — the conversion happens locally.
Are my M4A files uploaded to a server?
No. Files never leave your device. The entire M4A → M4B conversion runs locally in your browser, so your data stays private.
Can I convert multiple M4A files at once?
Yes — batch conversion is supported. Add as many M4A files as you like and convert them to M4B in one pass, then download the results together.
What is the maximum file size?
There is no fixed server-side limit because the conversion happens in your browser. Practical limits depend on the available memory and CPU of your device.
Will converting M4A to M4B reduce the quality?
Because both formats use lossy compression, the M4B output will not bring back any quality that has already been lost in your M4A file. Avoid repeated re-encoding to keep the best quality.
Does M4B support transparency?
No — M4B has no alpha channel. Transparent areas of your M4A file will be filled with a solid background colour in the converted file.
How will the file size change after converting M4A to M4B?
Both formats use comparable compression, so the M4B output will be similar in size to your M4A file — typically within 10–20% of each other.

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FREE

100% Free

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SIGNUP

No Signup Required

Start converting immediately without creating an account or sharing email address.

PRIVACY

Private & Secure

Your files never leave your device. All processing is completed locally for maximum privacy.

BATCH

Batch Conversion

Convert multiple files simultaneously to save time. Fast and efficient multi-file queue.

LOCAL

Runs in Browser

Utilizes advanced client-side WebAssembly technology to process files directly inside your tab.

FORMATS

200+ Formats

Supports a wide variety of formats including images, documents, audio, video, and more.

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