Stereo Width Calculator
Calculate the stereo width ratio from mid-side (M/S) processing using mid and side channel gain values in dB. Use this when mixing or mastering to quantify how wide your stereo image is.
About this calculator
In mid-side processing, the mid channel (M) carries the mono, center-focused signal, while the side channel (S) carries the stereo difference signal. Stereo width is expressed as the ratio of side level to mid level in the linear domain. Because gain values are given in decibels, each must be converted to a linear amplitude using the formula: amplitude = 10^(gain / 20). The stereo width ratio is therefore: Width = 10^(sideGain / 20) / 10^(midGain / 20). A ratio of 1.0 means equal mid and side energy — a balanced stereo image. Values above 1.0 indicate a wider, more spacious sound, while values below 1.0 indicate a narrower, more mono-leaning mix. This metric is essential when using M/S EQ or compression to control perceived width without phase issues.
How to use
Suppose your mid channel has a gain of 0 dB and your side channel has a gain of 6 dB. First convert each to linear amplitude: Mid = 10^(0 / 20) = 10^0 = 1.0. Side = 10^(6 / 20) = 10^0.3 ≈ 1.995. Then divide: Width = 1.995 / 1.0 ≈ 1.995. This means the side signal is nearly twice the level of the mid signal, indicating a very wide stereo image. If you then set side gain to −6 dB, Width = 10^(−0.3) / 1.0 ≈ 0.501, giving a much narrower, more mono result.
Frequently asked questions
What does a stereo width ratio of 1.0 mean in mid-side processing?
A stereo width ratio of 1.0 means the side channel and mid channel have exactly equal linear amplitude levels. In practice this represents a moderately wide, balanced stereo image — not fully mono, but not exaggeratedly wide. It occurs when both mid and side gains are set to identical dB values, so the linear ratio cancels to 1. Most well-mixed commercial tracks sit near or slightly above this value.
How does changing side gain affect the perceived stereo width of a mix?
Increasing the side gain raises the level of the stereo difference signal relative to the center, making the mix sound wider and more spacious. Decreasing it narrows the image toward mono. Each 6 dB increase in side gain roughly doubles the linear amplitude, which approximately doubles the width ratio. Audio engineers use this technique in M/S mastering to subtly open up or tighten a stereo mix without altering the center content.
Why is stereo width calculated using a linear ratio instead of just comparing dB values directly?
Decibels are a logarithmic scale, so you cannot directly divide two dB numbers and get a meaningful amplitude ratio. The formula 10^(gain / 20) converts each dB value back to its linear voltage or amplitude equivalent. Only after this conversion does division yield a true ratio that reflects how much louder one signal is than another. Using raw dB subtraction would give a difference in dB, not a dimensionless width ratio, which is a different — though related — concept.