# Audio Channel Tools - Stereo to Mono, Swap & Split Channels

> Free audio channel tools: stereo to mono (mix or L/R), mono to stereo, swap or split channels, mute one side, balance, fix phase, 5.1 to stereo.

- URL: https://qilingtools.com/en/audio/channels
- Category: Audio Tools (https://qilingtools.com/en/audio)
- Tags: [Audio](https://qilingtools.com/en/tags/audio), [Music](https://qilingtools.com/en/tags/music)
- Last updated: 2026-10-26
- Price: Free, no sign-up
- Privacy: Runs locally in the browser; files are never uploaded

Recording only plays in one ear? Two interview mics landed on the left and right channels? Left and right are reversed, the sound feels hollow, or you need a 5.1 movie track as headphone-friendly stereo? This tool gathers the everyday channel fixes in one place. Stereo to mono can mix both sides or keep only the left or right channel (handy when one side is noise). Mono to stereo copies the signal to both sides, or widens it into pseudo-stereo with complementary comb filters that still sum back to the original in mono. You can also swap left and right; split every channel into its own mono file (stereo gives L/R, 5.1 gives six files: FL, FR, FC, LFE and the surrounds); mute one side; adjust the balance; invert one channel by 180° to fix out-of-phase recordings that sound hollow and nearly vanish in mono; and downmix 5.1 to stereo with the ITU-R BS.775 coefficients, optionally including the LFE, normalized so nothing clips. Each file shows its channel layout (mono, stereo, 5.1…) after upload, whole batches can be processed at once, and the output keeps the original format or converts to MP3, M4A, WAV, FLAC, OGG or OPUS.

## How to use

1. Upload one or more audio files (videos work too) and check the channel layout shown
2. Pick a channel operation and set the source channel, balance or output format
3. Click Process and download the results (several files can be zipped)

## Features

- Stereo to mono: mix, left only or right only
- Mono to stereo: dual mono or widened pseudo-stereo
- Swap channels, mute one side, adjust balance
- Split channels into separate mono files (5.1 included)
- Invert one channel to fix phase problems
- ITU 5.1-to-stereo downmix with optional LFE
- Shows the input channel layout; batch processing
- Runs locally in your browser — no upload

## FAQ

### Why does my recording only play in one ear?

Usually a mono microphone was plugged into one input of a stereo interface, leaving the other side empty. Choose “Stereo to mono” with the side that has sound, or “Mono to stereo” as dual mono, and both ears will hear it.

### After converting to mono the audio got quieter or disappeared — why?

The left and right channels were out of phase, so they cancel when added. Use “Invert one channel” first, then convert to mono. A slight drop in level is normal: the mix takes half of each side so the sum cannot clip.

### Which coefficients does the 5.1 downmix use?

The ITU-R BS.775 standard: front left/right pass through, center and surround channels are mixed in at −3 dB, the LFE is left out unless you tick the option, and the gains are normalized so the downmix cannot clip.

### Are my files uploaded? Which formats work?

No — everything runs in your browser with FFmpeg (WebAssembly). MP3, WAV, M4A, FLAC, OGG, OPUS and more are supported, and you can drop in a video to process its audio track. The tool is free with no sign-up.

## Related tools

- [Convert Audio](https://qilingtools.com/en/audio/convert): Free online audio converter: convert between MP3, WAV, M4A, AAC, FLAC, OGG and OPUS with selectable bitrate. Powered by FFmpeg, processed locally, no upload.
- [Trim Audio](https://qilingtools.com/en/audio/trim): Free online audio trimmer: set start and end times to cut a clip from MP3, WAV, M4A and more. Make ringtones. Processed locally, no upload.
- [Merge Audio](https://qilingtools.com/en/audio/merge): Free online audio merger: join MP3, WAV and other audio files in order into one file, mixed formats supported. Processed locally, no upload.
- [Volume / Speed](https://qilingtools.com/en/audio/volume): Free online audio volume booster: amplify or reduce volume and change playback speed (0.5x to 3x without pitch change). Processed locally, no upload.
- [Audio Fade In/Out](https://qilingtools.com/en/audio/fade): Free online audio fade tool: add a fade-in at the start and a fade-out at the end of MP3, WAV and more, with any length. Batch supported, runs locally.
- [Normalize Audio](https://qilingtools.com/en/audio/normalize): Free online loudness normalizer: bring a batch of files to the same perceived loudness with EBU R128 / LUFS, or even out uneven speech with compression.
- [Split Audio](https://qilingtools.com/en/audio/split): Free online audio splitter: cut long recordings, album rips and audiobooks into parts by count, fixed length or specific time points, downloaded as a zip.
- [Mix Audio](https://qilingtools.com/en/audio/mix): Free online audio mixer: play voice, a backing track and background music together, with adjustable levels and a built-in limiter. Processed locally.