Reverberation Time Calculator
RT60 by Sabine and by Eyring, with the room volume, total absorption, Schroeder frequency and critical distance.
Results
RT60 by Sabine
0.6935
s
RT60 by Eyring
0.6401
s
Room volume
67.200
m³
Surface area of the room
104.000
m²
Total absorption
15.600
m² sabin
Schroeder frequency
203.18
Hz
Mean free path of a sound ray
2.5846
m
Absorption in the room now
15.600
m² sabin
Critical distance
0.561
m
What this tool does
Reverberation time is the room's memory: how long a sound takes to fall by sixty decibels after it stops. Sabine's formula is the one everybody quotes and it is accurate in a live room; Eyring's is the one to use when the room is well treated, because Sabine's answer never reaches zero however much absorption you add. Both are shown, and they part company above about a quarter absorption.
Formula
Sabine: RT60 = 0.161 V ÷ A · Eyring: RT60 = 0.161 V ÷ (−S ln(1 − ᾱ)) · A = S ᾱ
Variables
| Symbol | Meaning | Unit |
|---|---|---|
l | Room length | m |
w | Room width | m |
h | Room height | m |
al | Average absorption coefficient | — |
ex | Absorption already installed | m² sabin |
RT | RT60 by Sabine | s |
RE | RT60 by Eyring | s |
VO | Room volume | m³ |
SU | Surface area of the room | m² |
AB | Total absorption | m² sabin |
SC | Schroeder frequency | Hz |
MF | Mean free path of a sound ray | m |
NA | Absorption in the room now | m² sabin |
CD | Critical distance | m |
Worked example
- Room length6 m
- Room width4 m
- Room height2.8 m
- Average absorption coefficient0.15
- Absorption already installed0 m² sabin
- RT60 by Sabine0.6935 s
- RT60 by Eyring0.6401 s
- Room volume67.200 m³
- Surface area of the room104.000 m²
- Total absorption15.600 m² sabin
- Schroeder frequency203.18 Hz
- Mean free path of a sound ray2.5846 m
- Absorption in the room now15.600 m² sabin
- Critical distance0.561 m
Limitations
- The result is an estimate based only on the values you type. Real situations often include factors this calculator does not know about.
- The calculation runs at full precision and only the display is rounded. If you copy an intermediate value and retype it, small differences can appear.
- Mixing units is the most common source of error. Convert every input to the units shown next to each field before calculating.