Acoustic Panel Quantity & RT60 Calculator
Enter your room dimensions, measured reverberation time, target RT60, and panel absorption data. The calculator estimates the exact treatment area, rounds up to whole panels, and checks the RT60 after rounding.
Recommended panel count13
- Required treatment area (sq ft)
- 103.76
- Installed panel area (sq ft)
- 104
- Estimated achieved RT60
- 0.4
- Wall coverage
- 24.07%
- Current equivalent absorption (sq ft sabins)
- 88.2
- Additional absorption required (sq ft sabins)
- 88.2
Assumes the entered absorption coefficients apply at the frequency band being estimated.
How to use this calculator
- Choose feet or meters, then enter the finished inside room dimensions.
- Enter the current measured RT60 and the target RT60 for the same frequency range.
- Choose Sabine for ordinary rooms or Eyring when the room already has higher average absorption.
- Enter one panel face size and the absorption coefficients for the panel and the surface it covers.
- Use the rounded panel count and achieved RT60 together, not the count alone.
How the panel count is calculated
This calculator starts with a measured reverberation time and works backward to the added absorption needed to reach a target. It treats each panel as replacing the exposed wall or ceiling area underneath it, so the useful gain is the panel coefficient minus the covered surface coefficient.
For a rectangular room, V = L x W x H, S = 2(LW + LH + WH), and wall area is Sw = 2H(L + W). The Sabine constant is 0.049 when dimensions are in feet and 0.161 when dimensions are in meters.
With the Sabine model, current absorption is A0 = C x V / T0, target absorption is At = C x V / Tt, and required panel face area is X = max(0, (At - A0) / (ap - as)). ap is the panel absorption coefficient and as is the coefficient of the surface being covered.
With the Eyring model, the calculator first infers average absorption: a = 1 - exp(-C x V / (S x T)). It then converts the difference in average absorption back to treatment area: X = max(0, S x (at - a0) / (ap - as)).
After finding the exact area, the calculator divides by one panel's face area and rounds up to a whole panel. It then recalculates the achieved RT60 using the rounded installed area. That last step matters because a large panel can overshoot the target, especially in small rooms.
What moves the result most
The largest drivers are the gap between current and target RT60, room volume, and the net absorption gain of the panel over the surface it covers. A very absorptive panel over painted drywall adds much more modeled absorption than the same panel over carpet or heavy drape. Larger panels reduce the count, but they do not reduce the required total face area.
What this leaves out
The result is an energy-average reverberation estimate, not a full room design. It does not place panels, find first-reflection points, model flutter echo, predict bass trapping, or address isolation. Small rooms often have uneven modal behavior below the midrange, so octave-band measurements and listening tests are still important.
Worked example
Suppose a room is 15 ft long, 12 ft wide, and 8 ft high. Its measured RT60 is 0.80 seconds and the target is 0.40 seconds. With the Sabine model, the room volume is 1,440 cubic feet and the inferred current absorption is 0.049 x 1,440 / 0.80 = 88.2 sq ft sabins. The target absorption is 176.4 sq ft sabins, so the added absorption needed is 88.2 sq ft sabins.
A 2 ft by 4 ft panel has 8 sq ft of face area. If its absorption coefficient is 0.90 and the wall it covers is 0.05, each square foot adds 0.85 sq ft sabins. The exact treatment area is 88.2 / 0.85 = 103.76 sq ft, which rounds up to 13 panels. The installed area is 104 sq ft, the estimated achieved RT60 is about 0.40 seconds, and the panels cover about 24.07% of the wall area.
Common questions
How many acoustic panels do I need for my room?
The useful answer depends on the measured RT60, the target RT60, the room volume, and the tested absorption coefficient of the panels. This calculator uses those values to estimate treatment area, then rounds up to a whole panel count.
What RT60 should a home studio, podcast room, or listening room target?
Small speech and podcast rooms are often kept fairly short, commonly around 0.2 to 0.4 seconds in the midrange. Listening rooms and control rooms vary by size and design goal, so use a target that matches the room use and check it by frequency band when possible.
Should I use the Sabine or Eyring equation?
Sabine is a common starting point when average absorption is modest. Eyring tends to behave better as average absorption rises because it is based on the logarithmic decay of remaining sound energy after reflections.
Can I use NRC as the panel absorption coefficient?
NRC can be used for a rough broadband estimate, but it is a rounded average across selected midrange bands. For a design decision, octave-band absorption coefficients measured with the intended mounting method are more useful.
Why is the covered wall's absorption subtracted?
A panel does not add its full absorption on top of a perfectly reflective surface unless the covered surface was actually reflective. The modeled gain is the panel absorption minus the absorption the exposed wall, ceiling, or finish already had.
Does panel thickness or an air gap change the result?
Yes. Thickness, air gaps, spacing, edge exposure, fabric, and mounting method can change the absorption coefficient, especially at lower frequencies. Use coefficient data for the panel installed the way you intend to install it.