RT60 Reverb Time Designer

Reverberation time (RT60) is how long it takes sound to decay by 60 dB after the source stops. Different spaces want different amounts: a control room or vocal booth should be short and even so you hear the recording, not the room — studio acoustics typically aim for the lower half of the recommended range; a concert hall wants a long, enveloping tail. This tool starts from published recommended ranges for your room type, then uses the Sabine equation, RT60 = 0.161 · V / A, to work backwards: for a target RT60 and your room volume V, the total absorption the room must present is A = 0.161 · V / RT60, measured in metric sabins (m²). If you enter your room’s current RT60, it estimates how much absorption you have now and how much more you need, then turns that into a rough number of broadband panels using a typical panel absorption (stated in the result).

Two honest caveats. Sabine assumes sound is diffuse and absorption is spread around the room; in small, lightly furnished, or already very dead rooms it loses accuracy and the Eyring equation does better — it applies a logarithmic correction that prevents the systematic overestimate Sabine produces when average absorption exceeds about 0.3, and is especially important for treated control rooms and vocal booths. And these targets are mid-frequency values (typically 500 Hz–1 kHz octave bands) — real rooms almost always decay more slowly in the bass due to room modes and the reduced effectiveness of thin absorbers below 200 Hz, so plan corner bass traps separately and expect a gentle low-frequency rise, which is acceptable for music spaces and worth minimising in critical-listening environments like mastering suites. The bass trap calculator can help size low-frequency corner treatment once you have a mid-band RT60 target from this tool. Use this to set a goal and size your broadband acoustic treatment, then confirm the achieved RT60 by measuring.

The Sabine equation (RT60 = 0.161 · V / A, where A is total absorption in metric sabins) is the right default for live, lightly treated rooms where sound bounces many times before dying away. Its assumption of a diffuse, reverberant field holds well when average surface absorption is low (roughly below 0.2), so it gives reliable results in concert halls, large meeting rooms, and untreated recording spaces.

The Eyring equation (RT60 = 0.161 · V / (−S · ln(1 − ᾱ)), where ᾱ is the mean absorption coefficient averaged across all surfaces) adds a logarithmic correction that prevents the systematic overestimate Sabine produces in dead rooms. Once average absorption climbs above about 0.2 — typical of a treated control room, a vocal booth, or any room lined with thick broadband panels — Sabine predicts a longer RT60 than actually occurs, and Eyring is the more honest choice. As a rule of thumb: reflective room, use Sabine; absorptive or treated room, use Eyring. The RT60 Calculator lets you enter surface-by-surface absorption coefficients and switch between both formulas, while the Room Mode Calculator covers the low-frequency behaviour no RT60 formula addresses.