ACOUSTIC ROOM PLANNING TOOL
Acoustic Panel RT60 Calculator: Sabine Formula by Room
Enter room dimensions and a target RT60 to get the absorption the room needs, then the square metres of NRC 0.85 panel that provide it. See the Sabine formula behind every figure and the room types the result applies to.
Planning an import order? Use the same figures to estimate panel area and a complete material schedule.
RT60 REVERBERATION CALCULATOR
Calculate Room RT60 and Required Panel Area
Enter room dimensions and a target RT60. The calculator returns the room volume, the absorption the room needs, and the square metres of NRC 0.85 panel that close the gap.
01
Enter Your Room Details
m
m
m
s
Meeting room: 0.4–0.6 s.
α
NRC 0.85 = 0.85 sabins per m².
m²
2400 × 600 mm panel = 1.44 m².
sabins
Untreated room: sum of surface area × absorption coefficient.
Please enter valid positive room dimensions, target RT60 and panel NRC before calculating.
Calculation Results
Estimated Acoustic Panel Requirement
Panels Required with Waste
16
panels
Includes a 10% waste allowance and rounds up to the next complete panel.
Room Volume
90.00 m³
Target Absorption
29.0 sabins
Panel Area Required
20.0 m²
Panels Before Waste
14 pcs
Calculation Breakdown
Room volume
6 × 5 × 3 = 90.00 m³
Target absorption
0.161 × 90 ÷ 0.5 = 29.0 sabins
Absorption shortfall
29.0 − 12.0 = 17.0 sabins
Panel area
17.0 ÷ 0.85 = 20.0 m²
Before waste
20.0 ÷ 1.44 = 13.9 → 14 panels
With waste
14 × 1.10 = 15.4 → 16 panels
HOW IT WORKS
The Sabine Formula, in Plain Terms
RT60 is the time in seconds for sound to decay by 60 dB in a room. The Sabine formula estimates it from the room volume and the total absorption in the room.
The Formula
What It Contains
01
RT60
The time it takes for sound to decay by 60 decibels after the source stops. A short RT60 sounds dry and intelligible; a long RT60 sounds reverberant and echoey.
02
The Formula
RT60 = 0.161 × V ÷ A. Rearranged for the absorption a room needs: A = 0.161 × V ÷ RT60.
03
Volume V
Room volume in cubic metres, calculated from length × width × height.
04
Absorption A
Total absorption in sabins — the sum of every surface's area times its absorption coefficient: A = Σ (αᵢ × Sᵢ).
05
The Constant 0.161
Derived from the speed of sound in air at 20 °C. It is fixed for normal room temperatures.
Key Notes
When to Use It
Sabine vs Eyring
Sabine assumes a lightly absorbed room. In a treated room it overestimates RT60 by 15–40%. When the mean absorption passes roughly 0.20, use the Eyring correction instead.
Room Volume Limit
Statistical formulas lose reliability below roughly 50 m³ or above 1000 m³. Use the result as a guide, not a design, in small or unusual spaces.
The 500 Hz Band
Broadband RT60 is commonly taken as the average of the 500 Hz and 1000 Hz values. Check the room's target against the 500 Hz band before sizing the order.
NRC as First Approximation
NRC is a single number averaged across four frequencies. A rigorous design runs the Sabine formula per octave band, because low frequencies behave differently.
Not a Transmission Design
RT60 addresses absorption inside a room. Sound transmission through a wall — STC — is a different question and needs a different calculation.
Planning note: This page is an estimate, not an acoustic design. It uses NRC 0.85 as the panel's absorption as a first approximation. The full per-band data is in the technical data sheet — ask for it with your quotation.
TARGET REFERENCE
Target RT60 by Room Type
Reverberation time is specified per room type, and the targets below come from the named standards, not from Yuheng.
Recording studio
0.2–0.4 s
Design guidance
Classroom
0.4–0.6 s
ANSI S12.60 ≤0.6 s
Meeting room / private office
0.4–0.6 s
BS 8233, WELL v2
Open-plan office
0.5–0.8 s
WELL v2 ≤0.5 s; BS 8233 ≤0.8 s
Restaurant / dining
0.7–1.0 s
BS 8233 ≤0.8 s
Cinema
0.8–1.2 s
Design guidance
Concert hall
1.8–2.2 s
Design guidance
Before you size the order: these are design starting points. The figure that matters is the 500 Hz band — the broadband RT60 is commonly taken as the average of the 500 Hz and 1000 Hz values.
WORKED EXAMPLE
Worked Example — A Meeting Room
The numbers below use typical published material values and the verified NRC 0.85; they illustrate the method, not a specific project.
Example Project
6 m × 5 m × 3 m Meeting Room
Room Volume
90 m³
Target RT60
0.5 s
Existing Absorption
12 sabins
Panel NRC
0.85
Current State
Untreated Room, Measured RT60
1.2 s
RT60
1
Room Volume
6 × 5 × 3 = 90 m³
2
Total Surface Area
126 m² (floor, ceiling, walls)
3
Existing Absorption
Carpet + plasterboard ≈ 12 sabins
4
Current RT60
0.161 × 90 ÷ 12 ≈ 1.2 s
5
Target RT60
0.5 s — well below current
Current RT60
1.2
seconds
Treatment
Treated Room, Target RT60
0.5 s
Target
1
Room Volume
6 × 5 × 3 = 90 m³
2
Target Absorption
0.161 × 90 ÷ 0.5 = 29 sabins
3
Absorption Shortfall
29 − 12 = 17 sabins
4
Panel Area Required
17 ÷ 0.85 = 20 m²
5
Panel Count
20 ÷ 1.44 = 14 panels
Panel area required
20
m²
Same Room. Different Target.
The room volume and existing absorption are unchanged. Reducing RT60 from 1.2 s to 0.5 s needs about 17 sabins of added absorption — roughly 20 m² of NRC 0.85 panel.
+17
sabins needed
FROM ABSORPTION TO PANELS
From Absorption to Panels: The NRC 0.85 Bridge
The calculator's output is sabins — the total absorption the room needs. Panel manufacturers report NRC. Here is the bridge no consultancy calculator makes.
NRC 0.85 = 0.85 Sabins per m²
NRC 0.85 means 1 m² of panel provides roughly 0.85 sabins. The required absorption, divided by 0.85, gives the square metres of panel.
Panel area = Absorption shortfall ÷ NRCSabine vs Eyring
Sabine assumes a lightly absorbed room. In a treated room it overestimates RT60 by 15–40%. When the mean absorption passes roughly 0.20, use the Eyring correction.
RT60 = −0.161 × V ÷ (S × ln(1 − ᾱ))
Scope & Limits
What This Calculator Does Not Cover
This page is an estimate, not an acoustic design. It is not a design for rooms under roughly 50 m³ or over 1000 m³ — statistical formulas lose reliability outside that range. It uses NRC 0.85 as a first approximation, not the full per-band absorption data. It does not address sound transmission (STC) — blocking sound through a wall is a different question from absorbing it in a room. And it is not a quotation.
RT60 FAQ
Frequently Asked Questions
Common questions about RT60, the Sabine formula, target reverberation by room type, and panel quantities.
Offices and meeting rooms target roughly 0.4–0.6 s for speech intelligibility, with open-plan offices up to about 0.8 s under BS 8233. The target table above lists values by room type.
RT60 measures how long sound lingers in a room; NRC measures how much sound a single panel absorbs. RT60 is a property of the room, NRC is a property of the panel. The calculator connects the two.
Work out the absorption the room needs to hit its target RT60, subtract what the room already absorbs, then divide the shortfall by the panel's NRC. At NRC 0.85, one square metre of panel provides roughly 0.85 sabins.
It loses reliability below roughly 50 m³, because the sound field is no longer diffuse. Use it as a guide, not a design, in small or unusual spaces.
NRC is measured in a reverberation room per ISO 354, which the panel's test report follows. RT60 itself is measured per ISO 3382.