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M4AOpus

Convert M4A to Opus

This free M4A to Opus converter changes your MPEG-4 Audio (.m4a) file into a Opus Audio (.opus) file, right in your browser. There is nothing to install, no account to create, and no limit on how many files you convert.

100% private. Your file is processed locally in your browser with WebAssembly — it is never uploaded to a server, stored, or seen by anyone.

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The conversion runs on your own device using ffmpeg compiled to WebAssembly (ffmpeg.wasm), so your file is never uploaded to a server. Opus is best for low-bitrate voice and streaming, which is the usual reason to convert from M4A.

Why convert M4A to Opus?

  • Note: Opus has narrower support than M4A - convert only when a specific app or workflow needs it.
  • Opus compresses more efficiently than M4A, so expect a smaller file at the same quality.
  • Pick Opus when you need a file made for low-bitrate voice and streaming.

M4A vs Opus

PropertyM4AOpus
Full nameMPEG-4 AudioOpus Audio
ContainerMPEG-4Ogg
Typical codecAACOpus
CompatibilityWideModern players
LosslessNoNo
Best forApple Music and efficient playbackLow-bitrate voice and streaming

How to convert M4A to Opus

  1. Add your M4A file

    Drag and drop your .m4a file onto the upload area, or click to browse and pick it from your device.

  2. Start the conversion

    Click "Convert to Opus". Everything runs locally with ffmpeg compiled to WebAssembly (ffmpeg.wasm) - your file stays on your device.

  3. Wait a few seconds

    A progress bar shows the conversion. The first run is slightly slower while the engine loads, then it is cached.

  4. Download your Opus file

    When it finishes, download the .opus file straight to your device.

Frequently asked questions

Is this M4A to Opus converter free?
Yes. It is completely free with no signup, no watermark, and no limit on how many files you convert. It is supported by ads, which keeps the conversion itself free.
Are my files uploaded to a server?
No. The conversion runs locally in your browser using ffmpeg compiled to WebAssembly (ffmpeg.wasm), so your file is processed in memory on your own device and is never uploaded, stored, or seen by anyone.
Will I lose quality converting M4A to Opus?
The audio is re-encoded to Opus, which is lossy. At a sensible bitrate the difference is hard to hear, but converting back and forth repeatedly will degrade quality.
Will the file get smaller or larger?
Smaller. Opus (smallest) compresses more efficiently than M4A (small) at the same quality.
What is the difference between M4A and Opus?
M4A is MPEG-4 Audio (an MPEG-4 container, typically AAC); Opus is Opus Audio (an Ogg container, typically Opus). Opus is best for low-bitrate voice and streaming, while M4A is best for Apple Music and efficient playback.
How long does the conversion take?
Most files finish in a few seconds to under a minute, depending on length and your device. The first conversion is a little slower while the engine downloads and caches, then later runs start instantly.

Related conversions

MP3 → OpusWAV → OpusOGG → OpusM4A → MP3M4A → WAVM4A → AAC

Need more formats or options? Use the full Audio Converter.