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Stereo Width Meter
Measures the correlation between the left and right channels and shows how much level is lost when summed to mono.
Video & Audio
Nothing uploaded
No sign-up
Free, unlimited
Drop a stereo audio fileanalysed in this page — nothing is uploaded
Add a file to begin.
In short
Correlation between the left and right channels runs from +1 to −1: +1 means both channels carry the same signal and the image is mono, around 0 means they are unrelated and the image is wide, and negative means they partly cancel. The figure that actually matters is not the width but what happens when the track is summed to mono — which every phone speaker, club system, supermarket ceiling and mono Bluetooth speaker does. A very wide mix is only a problem when it collapses, and the parts that vanish are usually the ones a stereo-widening plug-in added.
How to use the Stereo Width Meter
- Drop a stereo file in.
- Read the correlation, then the mono figure.
- Investigate anything losing more than about 1 dB in mono.
About the Stereo Width Meter
The Stereo Width Meter measures the correlation between the left and right channels and shows how much level is lost when summed to mono. It runs as plain JavaScript inside the page, which means there is no upload step, no queue and no size limit imposed by a server — the only limit is your own device.
What people use it for
- Checking a mix before it goes to a club or radio.
- Finding out whether a "stereo" file is really mono.
- Diagnosing why a track sounds thin on a phone.
Details
| Correlation +1 | Both channels identical — mono |
|---|---|
| Around 0 | Wide, uncorrelated |
| Negative | Partly out of phase — cancels in mono |
| The real test | How much level the mono sum loses |
Correlation is measured across the whole file, so a track that is narrow in the verses and wide in the chorus averages to a figure describing neither. When the answer matters, analyse the sections separately.
Where this tool stops
A whole-file measurement on the sample values. It cannot show which frequencies are out of phase, which is what a proper phase-versus-frequency display in a DAW gives you.
Frequently asked questions
What correlation should I aim for?
There is no target. A close-mic'd voice sits near +1, a live orchestral recording around +0.5, and a heavily processed electronic track can sit near 0 and be perfectly fine. What is not fine is negative correlation, because that means the channels cancel — and the mono sum figure tells you how much.
Why does mono matter in 2026?
Because a great deal of listening is still mono. Phone speakers, most smart speakers, club and venue systems, shop and restaurant ceilings, and many Bluetooth speakers in mono mode all sum the channels. A mix that loses 3 dB and its bass when summed sounds broken in all of those.
It says my channels are bit-identical.
Then it is a mono recording stored in a stereo container. It sounds the same and takes twice the space. Worth converting if file size matters, and worth knowing before you spend time trying to widen something that has no stereo information at all.
Is there a limit on how often I can use the Stereo Width Meter?
It is free, with no account, no trial and no daily cap. Every video & audio tool on inputtesthub.com works the same way: open the page and use it.
Can you see what I put into this utility?
No. The Stereo Width Meter runs entirely in your browser using JavaScript. Because the work happens locally, the utility also keeps working if your connection drops, and closing the tab is all it takes to discard everything.
What is the Stereo Width Meter used for?
The most common reasons people reach for it: checking a mix before it goes to a club or radio. Finding out whether a "stereo" file is really mono. Diagnosing why a track sounds thin on a phone. It is built for exactly those cases rather than being a general-purpose tool with this bolted on.
Where does the Stereo Width Meter stop being reliable?
A whole-file measurement on the sample values. It cannot show which frequencies are out of phase, which is what a proper phase-versus-frequency display in a DAW gives you. Knowing where a tool stops being trustworthy matters more than the cases where it works.
What are the key numbers for the Stereo Width Meter?
Correlation +1 is Both channels identical — mono. Around 0 is Wide, uncorrelated. Negative is Partly out of phase — cancels in mono. These are printed on the page itself, so you do not have to take them on trust.
Is there a file size limit?
There is no limit set by us, because your file is never uploaded — the only ceiling is the memory your own browser will give the tab. Very large files simply take longer to process, and a phone will give up sooner than a desktop.
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