Stereo to Mono
Mix to mono, swap or split channels, fix one-sided audio.
Fix Audio That Plays in One Ear
A lecture recorded with one microphone often ends up in the left ear only; an interview may have each person on a separate side; a podcast upload may be twice the size it needs to be because a mono voice was saved as stereo. Open the file here and pick the fix: mix both channels to mono, keep one side, swap them, duplicate mono to both sides, pan the balance, or split the channels into two separate files.
Before you choose, the tool measures the file: how many channels it has, how alike they are (correlation), and whether one side is louder. If both channels turn out to be identical, it says so — converting that file to mono halves its size with no change at all.
Key features
- Eight channel operations: mono mix, left only, right only, swap, mono to stereo, pan, split, phase invert.
- Measured before you change anything — channel correlation and left/right balance.
- Equal-power panning, so moving the balance does not dip the level in the middle.
- Split to two mono files in one ZIP for separate editing.
- Preview and waveform of the result before you download it.
This tool does its work inside your browser using native Web APIs. The files and text you give it are processed on your device and are not uploaded to our servers.
How to use: Stereo to Mono
- Open the audio
Drop an MP3, WAV, M4A or other audio file onto the box. - Read the measurements
Check the channel count, correlation and balance to see what is wrong. - Choose the change
Pick mono, a single side, swap, pan or split from the list. - Listen and save
Play the result, then press Download WAV.
Technical specifications
| Processing location | Entirely in your browser — no server round trip |
|---|---|
| Data uploaded | None. Files and text never leave your device |
| Price | Free — no account, no trial, no usage cap |
| Category | Audio |
| Works offline | Yes, once the page has loaded |
| Browser support | Chrome 90+, Edge 90+, Firefox 90+, Safari 15+ |
| Interface languages | English, 中文, हिन्दी, Español, العربية |
Frequently asked questions
Will mixing to mono lose anything?
Only stereo width. Sounds panned hard left or right stay audible, but anything that was out of phase between the channels can get quieter — which is what the correlation figure warns about.
What does the correlation number mean?
Near 1 the channels carry the same sound (effectively mono). Near 0 they are unrelated, as in wide stereo. Below 0 they partly cancel, which is a sign of a phase problem.
How do I fix a voice that only plays on the left?
Choose “Keep the left channel only” to get a mono file, or “Mono → stereo” afterwards if the destination needs two channels.
Does mono really halve the size?
For WAV, yes — half the channels means half the data. For compressed formats the saving depends on the encoder.