Sabine Reverberation Time Calculator
Reverberation time, RT60, is the single most important measure of how a room sounds: it is how long sound takes to fade by 60 decibels after the source stops. The Sabine equation relates RT60 to two quantities, the room volume and its total sound absorption in sabins. This calculator applies the classic Sabine formula and reports the reverberation time. Enter the room volume and the total absorption (the sum of each surface's area times its absorption coefficient). The result is a reliable estimate for diffuse rooms of low to moderate absorption.
Sabine equation
RT60 = constant * V / A
V = room volume (m3)
A = total absorption (sabins)
constant = 0.161 (metric) or 0.049 (imperial, cubic feet)
Reverberation time rises with volume and falls as absorption increases. Adding absorptive surfaces (people, soft furnishings, acoustic panels) increases A and shortens RT60.
Worked example
A 200 m3 room with 40 sabins of total absorption gives RT60 = 0.161 * 200 / 40 = 0.81 seconds, a fairly controlled acoustic suited to speech and music rehearsal.
Reverberation time: frequently asked questions
What is reverberation time (RT60)?
Reverberation time, RT60, is the time it takes for sound in a room to decay by 60 decibels after the source stops. It is the primary objective measure of how live or dead a room sounds. Concert halls aim for around 1.8 to 2.2 seconds; speech rooms and studios aim much lower, often 0.3 to 0.6 seconds.
What is the Sabine equation?
RT60 = 0.161 times V divided by A in metric units, where V is room volume in cubic metres and A is total absorption in metric sabins. In imperial units the constant is 0.049 with volume in cubic feet and absorption in square-foot sabins. The constant comes from the speed of sound and the definition of 60 decibels of decay.
Where does the 0.161 constant come from?
It is 24 times the natural log of 10 divided by the speed of sound: 24 times 2.302585 divided by 343, which is about 0.161 seconds per metre. Wallace Sabine derived the relationship empirically around 1900 and it remains the standard estimate for diffuse, moderately absorptive rooms.
When is the Sabine equation less accurate?
The Sabine equation assumes a diffuse sound field and works best for rooms with low to moderate average absorption (below about 0.3). For highly absorptive rooms the Eyring equation is more accurate. This calculator uses the classic Sabine form; treat it as a reliable estimate, not an exact prediction.
Official sources
- International Organization for Standardization: ISO 3382 measurement of room acoustic parameters.
- U.S. National Institute of Standards and Technology: nist.gov.
Reviewed by the CalculatorHub team, edited by James Graham, 19 June 2026. See our methodology.