Audio tool

Convert MP3 Files to M4B on Your Device

Make a M4B copy of MP3 in your browser for spoken-word publishing. The MP3 source remains on this device while the browser prepares M4B.

Route MP3 → M4B

or drop here · up to 500 MB

Max 50 MB per file

Preview (optional)

When your browser supports it, your audio plays here. You can still convert your file if preview does not load.

Ready

Use upload name

Local conversion competes with other open apps for processor time during this MP3-to-M4B job.
Large MP3 inputs may take several minutes on older hardware.
Review the beginning and end of M4B after the download finishes.

M4B serves audiobooks and chapter-aware Apple playback, whereas MP3 commonly serves phones, websites, podcasts, and universal playback.
For MP3-to-M4B delivery, plan for chapter metadata varying by player.
After leaving MP3, the receiving app must support the streams encoded inside M4B, not only its extension.

MP3 to M4B taking too long? Check available memory; long, high-resolution sources need substantially more.
M4B converted from MP3 not opening? Test a compatible player and inspect the output streams.
Check whether the receiver supports this M4B variant: chapter metadata varying by player.

When does MP3 to M4B conversion make sense?

It is useful when MP3 media created for easy sharing must enter a M4B system designed for spoken-word publishing.

Where is the MP3 source processed?

The browser prepares M4B from MP3 on this device instead of sending the source to a remote conversion server.

How can I approve M4B converted from MP3?

Test the M4B file in the receiving app and compare duration, channels and loudness with the MP3 source.

Quick use cases