Stereo to mono. Fix one-sided calls, halve voice file size.
Drop a stereo file — a Zoom recording where you're only on one side, a podcast you want to make smaller, a single-source mic recording that wastes the second channel. We average the channels into proper mono. Output MP3 or WAV. Browser-only, no upload.
drop audio here
MP3, WAV, M4A, FLAC, OGG, AAC, or a video file.
What this is good for
- Fix a one-sided Zoom / Skype / Teams call recording — many call apps record each participant to a separate channel. Playback sounds bizarre. Mono averages them so everyone's at the same level.
- Cut podcast file size in half — single-host voice podcasts have no useful stereo content. Stereo MP3 at 128 kbps → mono MP3 at 128 kbps = same audio quality, half the file size, half the bandwidth cost.
- Phone call recordings — Pixel / Samsung call recorders often record stereo with phone audio on one channel and mic on the other. Mono makes it normal.
- Hearing aid accessibility — some hearing aids and assistive listening devices work better with mono content.
- Voice memo cleanup — some iPhone Voice Memos record stereo even though only one mic is active. Half the file size for the same content.
- Hardware samplers (SP-404, MPC, vintage) — many older samplers prefer mono samples. See our SP-404 WAV converter for full sampler prep.
- Whisper / transcription prep — speech models ignore stereo. Mono is the canonical input. See Audio for Whisper.
How mono mixdown works (the boring math)
For each sample position in the file, we take the left channel value, add the right channel value, divide by 2, write that to the output. That's it. Levels stay where they were (no clipping from doubling), and any content that was identical in both channels stays identical. Content that was hard-panned left or right gets reduced by 6 dB but doesn't disappear. Anti-phase content (rare in real recordings) does cancel out — but if you had truly anti-phase audio, you had bigger problems.
When NOT to convert to mono
- Music you care about — stereo is how mixes communicate space and instrument placement.
- Binaural recordings — the whole point is the stereo image. Mono destroys it.
- Field recordings with positional intent — birdsong recordings, urban soundscapes, anything where "where did that sound come from" matters.
- Anything heading to Spotify or Apple Music — they accept mono, but mainstream music distribution expects stereo.
FAQ
Why is my Zoom or Skype call recording one-sided?
Call apps often record each participant's audio to a separate channel — your mic to the left, theirs to the right. Played back, one person is in your left ear and the other in your right. Mixing to mono averages the two so everyone's at a normal level.
How much smaller does mono make my file?
Roughly half at the same bitrate. A 10 MB stereo MP3 at 128 kbps becomes about 5 MB in mono at 128 kbps. For voice this is essentially free savings.
Should I convert music to mono?
Usually not. Music uses stereo for spatial imaging and instrument separation. Mono is for voice, single-source recordings, accessibility, and legacy hardware.
Does converting to mono lose audio quality?
For voice and single-source content, no — there was no useful stereo to begin with. For music, the stereo image is collapsed but the frequency content is preserved (channels are averaged sample-by-sample).
What if I only want one channel, not both averaged?
Most "one-sided recording" use cases work better with averaging than with picking a single channel — the silent side contributes nothing, so averaging just halves the level uniformly. If you specifically need to isolate one channel, use a DAW like Audacity (see our M4A → WAV for Audacity page if your file is M4A).
Does my file upload?
No. The conversion runs entirely in your browser tab.