Is my audio file uploaded anywhere?

No. The entire conversion runs inside your browser using the Web Audio API and MediaRecorder. Your file is read from local memory and never sent to any server.

Why does the output say WebM instead of M4A on Chrome?

Chrome and Firefox do not support encoding AAC/M4A natively via MediaRecorder. They use their best available codec (usually Opus in a WebM container). Safari on macOS and iOS produces true M4A/AAC output. This is a browser limitation, not a tool limitation.

Will converting MP3 to M4A improve audio quality?

No. Converting from one lossy format (MP3) to another lossy format (AAC/M4A) does not recover discarded data. The output will sound similar to the source but goes through an additional encode step.

What sample rate does the output use?

The output uses the sample rate of the source MP3 (typically 44100 Hz or 48000 Hz) as decoded by the Web Audio API.

What is the maximum file size I can convert?

There is no hard limit, but MediaRecorder captures at playback speed: a 10-minute track takes about 10 minutes to encode. Very large files may also exhaust browser memory. Use a desktop converter for long files or batches.

MP3 to M4A Converter

Drop an MP3 and download the browser-supported output — M4A/AAC where available, otherwise a clearly labeled fallback format. Nothing is uploaded.

Select MP3 File

Drop MP3 here or click to browse Supports .mp3 files

Encoding is captured in real time: a 10-minute track takes about 10 minutes after decoding.

Converted file will appear here

Done!

Summary

This tool decodes your MP3 file in the browser using the Web Audio API, then re-encodes it via the MediaRecorder API. On Safari the output is a native M4A/AAC file; on Chrome and Firefox the browser selects the best supported codec (typically Opus in a WebM container). The entire conversion runs client-side — your audio data never leaves your device.

How it works

Click the drop zone or drag an MP3 file onto it.
The browser decodes the MP3 using the Web Audio API.
The decoded audio is played through MediaRecorder and captured in real time.
A download button appears — click it to save the converted file.
All processing is local; your file is never sent to any server.

Use cases

Convert MP3 files to M4A for playback on Apple devices and iTunes.
Reduce file size compared to WAV while keeping better compatibility than OGG.
Prepare audio clips for iOS apps or Apple Podcasts submissions.
Archive compressed audio in a widely supported container format.
Convert voice recordings from MP3 to M4A for use in iMovie or Final Cut.
Share audio in M4A format for better compatibility with Apple ecosystems.

Frequently Asked Questions

Last updated: 2026-05-29 · Reviewed by Nham Vu