Convert stereo audio to mono

Use this free stereo to mono converter to collapse a stereo recording down to a single mono channel, or expand a mono track back to stereo, and download the result as an MP3. Converting audio to mono merges the left and right channels into one, which makes smaller files that are perfect for voice, interviews, and podcasts. Whether you need to downmix stereo, merge audio channels, or create single-channel audio, everything happens right here in your browser. The tool runs entirely on your device with ffmpeg.wasm, so your audio is never uploaded and stays completely private.

🔒 100% private — files never leave your device

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How to use

  1. Select or drop an audio file (MP3, WAV, M4A, AAC, OGG and more).
  2. Choose To mono (1 channel) or To stereo (2 channels).
  3. Click Convert and wait for the engine to process it.
  4. Download your converted MP3.

Frequently asked questions

What does converting to mono do?

It merges the left and right channels into a single channel using ffmpeg's -ac 1. The result is a smaller file and is ideal for voice recordings, interviews, and podcasts where stereo separation adds little.

What audio formats can I convert?

You can load common formats such as MP3, WAV, M4A, AAC, OGG, and FLAC. Whatever you upload, the converted output is always saved as an MP3 encoded with libmp3lame at quality 2.

Is my audio uploaded anywhere?

No. Everything runs locally in your browser with ffmpeg.wasm; your audio never leaves your device and nothing is sent to a server.

Can I convert mono back to stereo?

Yes. Choose To stereo (2 channels) and the tool duplicates the track across two channels. Note that this does not recreate true stereo separation — it simply makes a two-channel file from the mono source.

Why is the first run slow?

The first run downloads a one-time ~30MB processing engine (ffmpeg.wasm) to your device. After that it is cached and runs offline, so later conversions start much faster.

Is there a file size limit?

There is no fixed limit, but because processing happens in your browser's memory, very large files depend on your device's available RAM. You can convert one file at a time.

About this tool

Free stereo to mono converter that runs 100% in your browser. Downmix stereo to a single channel or expand mono to stereo, download as MP3, nothing uploaded.

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