Reverberation time (RT60) is how long sound takes to fade by 60 dB after the source stops. It drives how clear speech sounds in a room. Enter the room and an average absorption below for a quick Sabine estimate.
How RT60 is calculated
The Sabine formula is RT60 = 0.161 x volume / absorption in metric, or 0.049 x volume in imperial, where absorption equals the total surface area times the average absorption coefficient. Bigger rooms reverberate longer; more absorptive surfaces shorten the tail.
Target RT60 by room type (guidance)
| Room | Typical RT60 |
|---|---|
| Recording / critical listening | ~0.3 s |
| Conference / classroom | ~0.4 to 0.7 s |
| Multipurpose / worship | ~0.8 to 1.2 s |
| Concert hall | ~1.5 to 2 s |
Frequently asked questions
What is RT60?
The reverberation time: seconds for sound to decay by 60 dB after the source stops. Long RT60 sounds echoey and hurts speech clarity; short RT60 sounds dry.
How is RT60 calculated?
Sabine: RT60 = 0.161 x volume / absorption (metric) or 0.049 x volume (imperial). Absorption is surface area times the average coefficient.
What is a good RT60 for speech?
About 0.4 to 0.7 s for speech and conferencing. Music spaces run longer (1 to 2 s); studios shorter (~0.3 s).
What absorption coefficient should I use?
About 0.1 live, 0.2 average furnished, 0.35 some treatment, 0.5+ heavily treated. This tool uses one average value for a quick estimate.
How accurate is the Sabine estimate?
Good for a first estimate in diffuse rooms. For precise design, sum each surface material's absorption and use frequency-dependent coefficients.
Tuning a room's audio? Key Digital audio solutions and matrix switchers route and process audio for clear, intelligible sound. Find a dealer to spec your project.