One audio channel converter for every left/right problem
This audio channel converter fixes the channel layout of a recording without touching anything else. Fold stereo to mono, copy a mono track to both speakers, mix a 5.1 or 7.1 film soundtrack down to stereo, swap left and right, pull out a single channel, flip the polarity of one side, or move the balance. The file keeps its format, sample rate and tags unless you ask for something different.
Typical jobs: an interview where each person was recorded on their own side of a stereo track, a lavalier mic that only reached the left channel, a stereo pair with one cable wired backwards, a movie rip that sounds thin on headphones because its dialogue sits in the centre channel, or speakers that were connected the wrong way round. Swaps, extractions and polarity flips of WAV files are bit-exact — the samples are moved, not recalculated.
How to use the Audio Channel Converter
- Drop your audio files on the upload area. The list shows each file’s channel layout (mono, stereo, 5.1, 7.1) along with its format, sample rate and bitrate.
- Choose a Conversion. Extra options appear for the channel to keep, the channel to invert, the balance position or the surround downmix.
- Keep Output format on “Same as original”, or choose WAV, FLAC, MP3, AAC, Opus or Ogg Vorbis and a bitrate.
- Press Convert channels. Files that the chosen conversion doesn’t apply to, such as a stereo file in a surround downmix, are skipped and explained.
- Listen to Before and After, check the table, and download each file or a ZIP.
Audio Channel Converter features
ITU surround downmix
5.1 and 7.1 fold down with the ITU-R BS.775 coefficients: front channels at full level, centre and surrounds at −3 dB, LFE left out unless you include it.
Clip-safe scaling
The downmix can be scaled so the sum of all channels never exceeds full scale, or left at full level for quiet material.
Bit-exact moves
Swapping, extracting and polarity-flipping WAV or FLAC audio copies the original sample values exactly.
Out-of-phase check
Stereo files are analysed when loaded; if left and right would cancel in a mono mix, the page warns you.
Balance control
Turns the opposite channel down while the favoured side stays at full level, with the change shown in decibels.
Batch and any format
Process several files at once and keep their own formats, or convert them all to one.
How 5.1 and 7.1 are folded to stereo
The left output is L + 0.707 × C + 0.707 × Ls (plus 0.707 × the back-left channel for 7.1), and the right output mirrors it. 0.707 is −3 dB, which keeps the centre dialogue at the same perceived loudness when it is shared between two speakers. With “Scale the mix so it can’t clip” ticked, both outputs are divided by the sum of the coefficients — 2.414 for 5.1 — so even a full-scale explosion in every channel cannot overload the stereo file.
| Channel (WAV order) | Left output | Right output |
|---|---|---|
| 1 · Front left | 1.000 | — |
| 2 · Front right | — | 1.000 |
| 3 · Centre | 0.707 | 0.707 |
| 4 · LFE | off (0.707 if included) | off (0.707 if included) |
| 5 · Surround / back left | 0.707 | — |
| 6 · Surround / back right | — | 0.707 |
| 7, 8 · Side left / right (7.1) | 0.707 (left) | 0.707 (right) |
Polarity, phase and balance
Inverting a channel multiplies every sample by −1. It sounds identical on its own, but if one microphone or speaker cable was wired backwards, the two sides fight each other: the stereo image feels vague and the bass disappears when the channels are mixed. Flipping the faulty side back restores it.
The balance control is not a pan. Moving it to the right turns the left channel down — by 6 dB at +50 and to silence at +100 — while the right channel stays exactly as it was. To position a mono source between the speakers, use the pan option in the Mono to Stereo Converter.
Good to know
- Channel numbers follow the standard WAV/SMPTE order (L, R, C, LFE, then surrounds), which most files use; if a downmix sounds wrong, check the source’s channel layout.
- For a plain stereo-to-mono mix with presets for podcasts and voice notes, the Stereo to Mono Converter is quicker.
- Not sure which side is which? Check your speakers with the Speaker Test first.
- MP3, Opus and Vorbis hold at most two channels; keep surround files as WAV, FLAC or AAC.
- Files are read with Mediabunny (MPL-2.0); FLAC, MP3, AAC and Vorbis output use libFLAC (BSD), LAME or libavcodec (LGPL) and libvorbis (BSD), all running locally.
Audio Channel Converter FAQ
How do I swap the left and right channels?
Choose “Swap left and right”, drop the file and press Convert channels. The audio channel converter moves the left samples to the right and vice versa without re-processing them.
How do I convert 5.1 audio to stereo?
Choose the surround downmix. Centre and surround channels are mixed in at −3 dB as recommended by ITU-R BS.775, and the result is scaled so it cannot clip.
My recording only plays in one ear. Can I fix it?
Yes. Use “Extract one channel” to keep the side that has the sound — you get a mono file that plays in both ears — or “Stereo → mono” if both sides carry something useful.
What does inverting the polarity do?
It flips the waveform upside down. On its own you won’t hear a difference, but it fixes stereo pairs where one side is out of phase and cancels the other when mixed to mono.
Does it change the quality?
WAV and FLAC stay lossless, and moving or flipping channels is bit-exact. Lossy files such as MP3 are decoded and re-encoded, at the original bitrate unless you choose another.
Is my audio uploaded?
No. Everything is processed in your browser on your own device.