What is a good correlation value?

For material that must survive mono, keep it above roughly zero; broadcast practice is loosely zero and up, and close to plus one is safest. Music can sit comfortably between plus zero point three and plus zero point eight, and very wide ambient material may hover near zero without being broken.

Why does a value near minus one matter?

Because the two channels are close to mirror images, so summing them to mono cancels much of the content instead of reinforcing it. The usual causes are a polarity inversion on one channel, a miswired cable, or over-aggressive side processing, and the fix is to correct the source rather than to hide the number.

Why is the trend split into quarters?

A single figure for a whole song can average a well-behaved chorus and a broken section into something that looks acceptable. Four spans are enough to reveal that a problem is local rather than general, and the quarters follow the file's own length rather than clock time.

What does the balance reading measure?

It compares the energy in the left channel with the energy in the right and reports the result in decibels relative to the right side. A positive figure means the left is louder, a negative one the other way, and a dash appears when a channel is silent and no ratio exists.

Can it fix phase problems?

No, it only measures them. Once you know a section is out of phase, the correction belongs with the channel tools, where a polarity inversion can be tested or a mid-side rebuild can be attempted, and the meter can then be run again to confirm the change.

Phase Meter

You Might Also Need

Correlation Meter

Measure stereo correlation

Goniometer / Vectorscope

Visual stereo image analysis

Channel Inverter

Invert audio channel polarity

Mid/Side Processor

Process mid and side separately

Phase Meter reports how alike the two channels of a stereo file really are, giving a correlation figure between minus one and plus one. It also shows how that figure moves across the file and which side is louder.

What is Phase Meter?

A single correlation value summarises the relationship between left and right, and its meaning is direct: near plus one the channels are effectively the same, near minus one they are mirror images, and around zero they carry largely independent material.

What the panel reports:

The overall correlation, printed to three decimals and labelled in words as effectively mono, correlated, wide or decorrelated, out of phase in places, or polarity inverted.
A horizontal bar centred on zero, with the filled position showing which side of the midpoint the value falls on.
A trend row splitting the file into quarters, so a problem confined to one section shows up even when the whole-file figure looks acceptable.
An L/R balance figure in decibels, reported as left relative to right, with a dash when either side is silent.

Correlation is computed as a normalised inner product of the two channels across the file: the sum of their products divided by the product of their energies. That normalisation is what makes the result comparable between a loud master and a quiet demo, and it is also why the calculation needs a guard against silence, where the denominator would otherwise be zero. The trend quarters come from running the same computation over four equal spans, which matters in practice because a whole-file figure can average a good chorus and a broken verse into a number that looks fine. The balance reading is a separate comparison of the two channels' energy, so it answers a different question: not whether the sides agree, but whether one is consistently louder. Stated plainly, the panel is a phase correlation measurement with a mono-compatibility verdict attached to it. The overall figure describes the file as a whole, while the quarter trend shows how that correlation shifts across four spans, so a reading that looks acceptable on average can still be shown to hide a passage that folds up when summed. Nothing in the panel changes the audio, so it is a diagnostic to run before delivery rather than a repair to run after a complaint arrives.

What the meter cannot tell you:

A mono file is rejected outright, since there is no second channel to compare with.
The whole-file figure can hide a section that is seriously out of phase if the rest is well correlated.
No frequency dependence is shown, so a problem confined to the bass or the top end reads as one averaged number.
Nothing is corrected here; the measurement only reports what is present.
The trend is limited to four quarters, so short trouble spots inside a long section may not appear.
Silence in one channel leaves the balance figure blank rather than reporting a value.

Use it before delivering anything that may be summed to mono: a phone speaker, a club system with a mono sub, a television broadcast, or a podcast played on a single speaker. A value near plus one collapses safely, a value near minus one partially cancels, and the usual cause of the latter is a polarity flip on one channel or a mid-side processing mistake.

How to use Phase Meter

Drop a stereo audio file onto the panel; mono files are reported as unsupported rather than analysed.
Read the correlation value against its descriptive label to judge mono compatibility.
Look along the trend row to check whether all four quarters behave the same way.
Compare the L/R balance figure to see whether one channel carries more energy than the other.

When to use Phase Meter vs related tools

Phase Meter is the diagnostic for mono compatibility, so it belongs in the chain before any delivery that might be summed to one channel. Correlation Meter presents the same measurement as a broadcast-style needle meter, and Goniometer / Vectorscope shows the stereo field as a shape rather than a number. If the reading points at a specific fault, Channel Inverter can test a polarity flip and Mid/Side Processor can rebuild the sides.

Privacy & Security

This tool runs entirely in your browser — no data ever leaves your device. There is no server round-trip, no upload, no logging, and no account required. Your input is processed locally using client-side JavaScript and is never stored, transmitted, or accessible to anyone else. When you close the tab, everything disappears.