RT60 Reverb Time Calculator
Estimate a room’s reverberation time with the Sabine equation from its volume, surface area and average absorption coefficient.
How it works
RT60 = 0.161 · V ÷ A, where A = surface area · average absorption coefficient
RT60 is the time for a sound to decay by 60 dB after the source stops — the classic measure of how "live" a room is. Sabine’s equation says it depends on the room volume divided by its total absorption: bigger rooms ring longer, and more absorptive surfaces shorten the tail. The 0.161 constant carries the units for volume in cubic metres and absorption in metric sabins.
Worked example
A 72 m³ room with 108 m² of surface and an average absorption coefficient of 0.2 has 108 × 0.2 = 21.6 sabins of absorption. RT60 = 0.161 × 72 ÷ 21.6 ≈ 0.54 s — a well-controlled listening room.
Sources: Sabine equation — Wikipedia
Frequently asked questions
What RT60 should a room have?
It depends on use: recording control rooms aim for 0.2–0.4 s, home theatres and living rooms 0.4–0.6 s, classrooms around 0.6 s for speech clarity, and concert halls 1.8–2.2 s for musical warmth. Shorter is not always better — an overly dead room sounds unnatural.
What is a metric sabin?
One metric sabin is the absorption equivalent of one square metre of a perfect absorber. A wall’s absorption in sabins is its area times its absorption coefficient, so 10 m² of material with a coefficient of 0.5 provides 5 sabins.
When does the Sabine formula break down?
Sabine assumes a diffuse field and moderate absorption. In very dead rooms (average coefficient above roughly 0.3) it overestimates reverb time; the Eyring equation, which uses ln(1 − average coefficient), is more accurate there. For typical rooms Sabine is close enough.
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