Stereo Width

Make a mix feel wider or tighter, and check that it still holds up when played in mono.

or drop it here

MP3, WAV, M4A, FLAC, OGG, Opus, AIFF, WMA, AMR and the sound of most videos. Files stay on your device.

How it works

Choose a stereo file.
Set the width: below 100% narrows, above 100% widens.
Check the mono-compatibility correlation while previewing.
Export and download.

Mid/side width

The tool splits the stereo signal into mid (what both channels share, usually the centre) and side (what differs between them). Width scales the side signal: 0 gives mono, 100 percent leaves the file unchanged, and values up to 200 percent double the side. Narrowing tightens a mix; widening spreads it out.

Checking mono compatibility

Wide mixes can sound thin or lose their centre when played on one speaker, such as a phone or a club system. Press Check mono compatibility to measure the whole file before and after the change. The table shows the correlation between left and right (+1 is mono-like, 0 unrelated, −1 opposite phase), the lowest correlation in any second, how much the level drops when left and right are summed, and the stereo width on a 0 to 100 scale.

A drop of less than 1 dB when summing to mono is good, 1 to 3 dB deserves a listen on one speaker, and more means real cancellation. These thresholds are rules of thumb, not a standard.

Limits

The tool needs a stereo file. A file with identical channels has no side signal, so widening changes nothing. Widening does not create stereo information that is not in the recording.

Questions

How wide is too wide?

If the check shows a mono level loss over 3 dB or the correlation goes negative, the mix will lose content on a single speaker. Keep widening modest, usually under 150 percent.

Can I turn a mono file into stereo here?

No. A mono or dual-mono file has no side signal. Use the reverb tool for a sense of space.

What does the correlation number mean?

It compares the left and right channels. +1 means they are the same, 0 means they are unrelated, and negative values mean they partly cancel when summed.

Does the measurement change my file?

No. It only reads the audio and shows the numbers; only Apply width changes it.