Reverberation Time (RT60)
RT60 = 0.161 × V / (α × S)
Quick answer
This calculator solves RT60 = 0.161 × V / (α × S) for Reverb Time. With Room Volume 0.1 m³, Avg Absorption Coeff 0.5, Total Surface Area 100 cm², the result is 3.22 s. It solves in 3 directions, so you can enter the values you have and get the one you need.
Calculator
Formula
Description
The Sabine equation calculates the reverberation time RT60, defined as the time for sound to decay by 60 dB after the source stops. It depends on the room volume, the total surface area, and the average absorption coefficient of the surfaces. Larger rooms have longer reverberation times, while more absorptive surfaces reduce it. The constant 0.161 applies when volume is in cubic meters and area in square meters. RT60 is the most important single parameter in room acoustics, determining speech intelligibility and musical character.
Variables
- RT60 — Reverberation time for 60 dB decay (s)
- V — Room volume (m³)
- α — Average absorption coefficient (0-1, dimensionless)
- S — Total surface area of the room (m²)
Practical Notes
Optimal RT60 depends on the use: 0.3-0.5s for recording studios, 0.6-1.0s for speech/conference rooms, 1.5-2.5s for concert halls, and 3-8s for cathedrals. Absorption coefficients vary with frequency: carpet absorbs high frequencies well (α≈0.5) but not lows (α≈0.05), while bass traps target low frequencies. The Sabine equation is most accurate for rooms with relatively uniform absorption.
Symbols and units
| Symbol | Meaning | Default unit | Accepted units |
|---|---|---|---|
| RT60 | Reverb Time | s | ps, ns, µs, ms, s, min, h |
| V | Room Volume | m³ | m³ |
| alpha | Avg Absorption Coeff | — | — |
| S | Total Surface Area | m² | mm², cm², m² |
Step by step
- 1. What you know: Room Volume 0.1 m³, Avg Absorption Coeff 0.5, Total Surface Area 100 cm²
- 2. The relation: RT60 = 0.161 × V / (α × S)
- 3. Substitute: V = 0.1 m³, alpha = 0.5, S = 100 cm²
- 4. Result: Reverb Time = 3.22 s
Worked examples
Minimum range
Given: Room Volume 1 × 10⁻⁴ m³, Avg Absorption Coeff 0.025, Total Surface Area 10 mm²
Result: Reverb Time = 1.073 min
Low range
Given: Room Volume 0.001 m³, Avg Absorption Coeff 0.25, Total Surface Area 1 cm²
Result: Reverb Time = 6.44 s
Typical
Given: Room Volume 0.1 m³, Avg Absorption Coeff 0.5, Total Surface Area 100 cm²
Result: Reverb Time = 3.22 s
High range
Given: Room Volume 1 m³, Avg Absorption Coeff 0.8, Total Surface Area 1 m²
Result: Reverb Time = 0.2012 s
Maximum range
Given: Room Volume 10 m³, Avg Absorption Coeff 8, Total Surface Area 10 m²
Result: Reverb Time = 20.13 ms
Solving for each variable
Solve for Reverb Time
Room Volume 1 × 10⁻⁴ m³, Avg Absorption Coeff 0.025, Total Surface Area 10 mm² → 1.073 min
Solve for Room Volume
Reverb Time 100 µs, Avg Absorption Coeff 0.025, Total Surface Area 10 mm² → 1.55 × 10⁻¹⁰ m³
Solve for Total Surface Area
Reverb Time 100 µs, Room Volume 1 × 10⁻⁴ m³, Avg Absorption Coeff 0.025 → 6.44 m²
How Reverb Time changes with Room Volume
| Room Volume (input) | Reverb Time (result) |
|---|---|
| 0.01 m³ | 0.322 s |
| 0.025 m³ | 0.805 s |
| 0.05 m³ | 1.61 s |
| 0.075 m³ | 2.415 s |
| 0.1 m³ | 3.22 s |
| 0.15 m³ | 4.83 s |
| 0.2 m³ | 6.44 s |
| 0.4 m³ | 12.88 s |
| 0.7 m³ | 22.54 s |
| 1 m³ | 32.2 s |
The same result in other units
| Unit | Value |
|---|---|
| µs | 3220000 |
| ms | 3220 |
| s | 3.22 |
| min | 0.05367 |
| h | 0.0008944 |
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<p><a href="https://vbatpower.com/formulas/reverberation-rt60/">Reverberation Time (RT60)</a> Calculator by vbatpower.com</p>Frequently asked questions
How do you calculate Reverberation Time (RT60)?
Use RT60 = 0.161 × V / (α × S). With Room Volume 0.1 m³, Avg Absorption Coeff 0.5, Total Surface Area 100 cm², Reverb Time works out to 3.22 s.
What is the formula for Reverberation Time (RT60)?
The formula is RT60 = 0.161 × V / (α × S). The Sabine equation calculates the reverberation time RT60, defined as the time for sound to decay by 60 dB after the source stops.
How do you find Room Volume when you know the other values?
Rearrange for Room Volume: with Reverb Time 100 µs, Avg Absorption Coeff 0.025, Total Surface Area 10 mm², Room Volume is 1.55 × 10⁻¹⁰ m³.
How do you find Total Surface Area when you know the other values?
Rearrange for Total Surface Area: with Reverb Time 100 µs, Room Volume 1 × 10⁻⁴ m³, Avg Absorption Coeff 0.025, Total Surface Area is 6.44 m².
What units does Reverberation Time (RT60) use?
Reverb Time is shown in µs, ms, s, min, h. Values are held in SI base units internally, so you can mix prefixes without converting by hand.
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