Stereo to Mono Converter (Free, Online, No Upload)

Convert any stereo audio file to mono right in your browser. Nothing gets uploaded to a server. Mono audio is standard for podcasts, voice recordings, and phone systems where stereo adds file size without benefit. The conversion runs locally on your device.

Try it in your browser

Loading FFmpeg engine... (~31 MB)

Use the API

curl -X POST https://renderio.dev/api/v1/run-ffmpeg-command \
  -H "X-API-KEY: ffsk_your_api_key" \
  -H "Content-Type: application/json" \
  -d '{
  "ffmpeg_command": "-i {in_audio} -ac 1 {out_audio}",
  "input_files": {
    "in_audio": "https://example.com/input.mp3"
  },
  "output_files": {
    "out_audio": "output.mp3"
  }
}'

Need an API key? Get your free API key to start processing files programmatically.

Common Variations

WAV output

-i input.wav -ac 1 output.wav

Left channel only

-i input.mp3 -af "pan=mono|c0=FL" output.mp3

Right channel only

-i input.mp3 -af "pan=mono|c0=FR" output.mp3

Related Operations

Free Mono to Stereo Audio Converter Online | RenderIO Normalize Video Audio Online Free, No Upload | RenderIO MP3 to WAV Converter Online Free, No Upload | RenderIO Extract Audio from Video Online Free - No Upload | RenderIO

Need to process at scale?

Automate this with the RenderIO FFmpeg API. Process thousands of files programmatically or through no-code video automation.

Get your API key