Convert stereo audio to mono online

How to turn stereo into mono, step by step

The Channel Mixer window opens as soon as your file has loaded.

1. Click Open a stereo file, or use File ▸ Open… (Ctrl+O), and choose your audio file.
2. To change only part of the file, select it first. With nothing selected, the mix applies to the whole file.
3. If the window is not open yet, choose Effects ▸ Amplitude ▸ Channel Mixer…
4. In Presets, choose Mono Sum. It sets the four sliders to 50%, so each new channel is half the left plus half the right.
5. Press Preview to listen, then click OK.
6. For a file with one channel instead of two identical ones, open Edit ▸ Convert Sample Type… (F11), set Channels to Mono and click OK.
7. Save the result with File ▸ Save As… as WAV, FLAC, MP3 or Ogg Vorbis.

Mono Sum or Convert Sample Type?

Both give the same mix of the two channels. They differ in what the file looks like afterwards.

• Mono Sum in the Channel Mixer keeps a stereo file with two identical channels. It works on a selection, so you can fold a single passage, and the file still matches other stereo material.
• Edit ▸ Convert Sample Type… with Channels set to Mono averages the channels into one. A WAV file takes half the space, and an MP3 or Ogg saved from it is mono too.

Other jobs for the Channel Mixer

Each slider sets how much of the old left or right channel goes into the new left or right, from -100% to 100%. The presets cover the usual cases:

• Both = Left and Both = Right keep one side only. Useful when one channel of a recorder holds a bad microphone or just noise.
• Swap Channels exchanges left and right.
• Vocal Cut (center) subtracts one channel from the other, which removes what sits in the middle of the mix, often the lead voice. The two channels end up opposite in polarity, so do not fold that result to mono: it would cancel to silence.

Check the mono version before you save

Summing changes the balance. A sound that was only in one channel comes out 6 dB quieter, and Effects ▸ Amplitude ▸ Normalize… can bring the overall level back up.

If the mono version sounds thin or hollow, one channel is probably inverted in polarity and the two cancel each other. Undo with Ctrl+Z, choose Edit ▸ Edit Channel ▸ Right Channel, apply Effects ▸ Invert, go back to Edit ▸ Edit Channel ▸ Both Channels and mix again.

Going the other way: mono to stereo

Edit ▸ Convert Sample Type… with Channels set to Stereo copies the single channel to both sides. The file becomes stereo, but it still sounds centered: stereo width that was never recorded cannot be recovered.

For a sense of space, convert first and then add an effect, such as the Haas Widener preset of Effects ▸ Delay Effects ▸ Multitap Delay…, which delays one side slightly. Use it with restraint and preview it.