RT60 Reverberation Time Calculator

RT60 equals 0.161 times the room volume in cubic metres divided by the total absorption in metric sabins. It estimates the time for sound to decay by 60 decibels after the source stops. This calculator uses the constant 0.161, the standard value for metres.

A metric sabin is the absorption of one square metre of a perfectly absorbing surface. Total room absorption is the sum of every surface area multiplied by its absorption coefficient. One sabin removes as much energy as one square metre of an open window would.

The 'Total absorption' button takes the sabins figure directly. The 'Area and coefficient' button multiplies a surface area in square metres by one average coefficient to get the sabins for you, which is handier when you know the room size but not the sabins.

It is metric only. Volume is in cubic metres, area is in square metres, and absorption is in metric sabins. If your figures are in feet, convert first, since the 0.161 constant is tied to metres. The result is always in seconds.

An absorption coefficient is the fraction of sound energy a surface soaks up, so 0 is perfectly reflective and 1 is perfectly absorptive. The calculator rejects a coefficient at or below 0 or above 1 because those values are not physical for a single surface.

The reverberation time is shown to three decimal places and the absorption to two. For example, volume 200 m3 with 240 m2 at coefficient 0.15 gives 36 sabins and an RT60 of 0.894 seconds.

It depends on the room. Home studios and control rooms often target roughly 0.2 to 0.4 seconds, small offices and classrooms sit a little higher, and concert halls are deliberately longer to add warmth. Shorter times mean a drier, more controlled sound.

Sabine assumes absorption is spread evenly and works best in fairly reverberant rooms. In very dead rooms or where absorption is bunched on one surface it overestimates RT60, and it ignores air absorption at high frequencies. Treat the figure as a design starting point.

Yes. Every calculation runs locally in your browser and nothing is uploaded to a server, so your room measurements never leave your device.