Reverberation Time Calculator (RT60 — Sabine Equation)
Enter room dimensions and an average absorption coefficient to compute RT60 — the time sound takes to decay by 60 dB after the source stops — using Sabine's classic equation.
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Time for sound to decay by 60 dB after the source stops (Sabine equation)
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Room volume
10 × 8 × 3 = 240 m³ - 2
Total surface area
2 × (10 × 8 + 10 × 3 + 8 × 3) = 268 m² - 3
Total absorption
0.15 × 268 = 40.2 m² sabinsA = α × total surface area. - 4
Reverberation time (RT60)
0.161 × 240 ÷ 40.2 = 0.96
How does this calculator work?
Reverberation time RT60 = 0.161 × V / A (Sabine, SI units), where V is room volume in m³ and A = α × surface area in m² sabins. Below 0.5 s suits speech and recording; 0.8–1.5 s suits chamber music; above 1.5 s suits orchestral music and large concert halls.
Formula
How this is calculated
Reverberation time (RT60) is the most important single metric in room acoustics: the duration, in seconds, for a sound to decay by 60 dB after the source is switched off. A space with a short RT60 sounds dry and intimate — recording booths and home-theatre rooms aim for 0.2–0.4 s. A long RT60 sounds lively and reverberant — cathedrals can exceed 5–10 s.
Wallace Sabine derived the first accurate formula in 1900: RT60 = 0.161 × V / A, where V is room volume in cubic metres and A is total acoustic absorption in square-metre sabins. Total absorption is the sum over all room surfaces of each surface's area multiplied by its absorption coefficient α (a dimensionless number from 0, perfectly reflective, to 1, perfectly absorptive). This calculator uses a single average α for the whole room — a practical simplification when exact material data for every surface is unavailable.
Sabine's equation assumes a diffuse sound field and works best for medium-sized rooms where no single dimension dominates. It tends to overestimate RT60 for very large or unusually proportioned spaces. More accurate predictions require Eyring's or Fitzroy's equations, or computer simulation. The absorption coefficient values in the hint are rough midpoints; real-world α varies significantly by frequency, material, and product specification.
Frequently asked questions
For recording or podcasting, aim for RT60 below 0.4 s. You can reduce it by adding acoustic panels, heavy curtains, bookshelves, and soft furnishings — all raise the average absorption coefficient.
α ranges from 0 (all sound reflected, like a concrete wall) to 1 (all sound absorbed, like a thick acoustic panel). An average furnished room sits around 0.10–0.20; a heavily treated studio may reach 0.50 or more.
Sabine's equation is a reliable estimate for small-to-medium rooms with reasonably even absorption. For very large venues, long narrow rooms, or spaces with heavily uneven absorption, Eyring's equation or acoustic simulation software will give more accurate results.
Also known as
TG we-Calculate Editorial Team. (2026). Reverberation Time Calculator (RT60 — Sabine Equation) [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/reverberation-time-calculator
TG we-Calculate Editorial Team. "Reverberation Time Calculator (RT60 — Sabine Equation)." TG we-Calculate. 2026. https://we-calculate.com/calculator/reverberation-time-calculator.
TG we-Calculate Editorial Team, "Reverberation Time Calculator (RT60 — Sabine Equation)," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/reverberation-time-calculator
@misc{wecalculate_reverberation_time_calculator, title = {Reverberation Time Calculator (RT60 — Sabine Equation)}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/reverberation-time-calculator}}, year = {2026}, note = {TG we-Calculate} }
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