Free Tool
Enter your room and what you use it for. We'll tell you how many panels it actually takes — and, just as usefully, what a smaller number would get you.
The common choice. Strong above 250 Hz.
13
2 ft × 4 ft (60 × 120 cm) panels to bring this room from 0.71s down to 0.30s, covering 27% of your wall area.
Almost nobody buys to a target — they buy to a budget. Here's the trade.
| Panels | Wall covered | Result | vs now |
|---|---|---|---|
| 2 | 4% | 0.59s | −17% |
| 4 | 8% | 0.51s | −29% |
| 6 | 12% | 0.44s | −38% |
| 8 | 17% | 0.39s | −45% |
| 12 | 25% | 0.31s | −56% |
| 16hits your target | 33% | 0.26s | −63% |
| 20hits your target | 42% | 0.22s | −69% |
| 24hits your target | 50% | 0.19s | −73% |
Diminishing returns are real. The first few panels do far more than the last few — going from nothing to six panels changes a room audibly; going from eighteen to twenty-four is a refinement.
| Reverb time | 125 | 250 | 500 | 1k | 2k | 4k |
|---|---|---|---|---|---|---|
| Now | 2.51 | 2.51 | 0.91 | 0.51 | 0.39 | 0.36 |
| With 13 panels | 1.24 | 0.65 | 0.34 | 0.25 | 0.22 | 0.20 |
Still over target at 125 Hz, 250 Hz, 500 Hz. This is normal and it is not a failure of the panels. Flat wall absorbers get progressively weaker as frequency drops, so the bass decays more slowly than everything else. If the room still feels heavy or boomy after treatment, that residue is what you're hearing — and the answer is depth in the corners, not more panels on the walls.
What it takes to reach 0.3s with each option.
| Product | Panels | Wall covered |
|---|---|---|
| 100 mm (4 in) fabric-wrapped panelThe thick stuff. Works low and high. | 12 | 25% |
| 50 mm (2 in) fabric-wrapped panel, flat on wallThe common choice. Strong above 250 Hz. | 13 | 27% |
| 50 mm (2 in) panel, spaced 300 mm off the wallSame thickness, air gap behind. Far better in the bass, slightly weaker in the mids — so it needs a few more panels for the same mid-band result. | 18 | 37% |
| Thin acoustic foam tileCheap, and almost useless below 500 Hz. | can't | — |
The spots on the side walls where sound bounces from your voice to the microphone, or from the speakers to your head. Slide a mirror along the wall — where you can see the source from your listening position, that's the point. Two panels here beat six anywhere else.
The wall you face reflects straight back into the mic. The wall behind you sends a delayed copy of your voice after it. Both matter more than the corners of the room you never point anything at.
A cloud panel directly overhead is one of the most effective single placements in a small room, and it uses space nothing else wants.
Mounting a panel a few centimetres off the wall rather than flat against it extends its reach downward in frequency, at no cost. Spacers, or just longer screws with washers.
More than most people expect, and fewer than the number required to reach a studio specification. Both halves of that sentence matter.
The honest answer depends on the volume of your room, how absorbent it already is, and what you want to use it for. A carpeted spare bedroom already has meaningful absorption on the floor and needs far less help than the same room with hard flooring. A large living room with a wooden floor and big windows may need thirty panels to reach a recording target — which is usually the point at which you decide you don't need a recording target in your living room.
This is why the calculator shows a curve rather than a single number. Six panels in an untreated spare room is a transformation you will hear immediately. Getting from there to a studio-grade 0.3 seconds might take another dozen, and for most people that second dozen isn't worth it.
Most panel calculators use the Sabine equation, which assumes sound is evenly distributed and absorption is fairly low. Those assumptions hold in a big, mostly-reflective hall. They fall apart in a small room you have deliberately covered in absorption, where Sabine overestimates how much treatment you need — sometimes by twenty or thirty per cent.
The Eyring-Norris formula handles high average absorption correctly, so it is what we use here. In practice it means this calculator recommends fewer panels than most, and we think it is right to.
Run the comparison table with thin foam selected and you will often see that it cannot reach the target at any sane coverage. That is not editorialising, it's the measured absorption coefficients doing the talking: thin foam absorbs around 0.07 at 125 Hz and 0.20 at 500 Hz, against roughly 0.46 and 1.00 for a 100 mm fabric-wrapped panel.
Foam does remove high-frequency flutter, and a room covered in it will sound different. But if the complaint is that voices sound hollow or the room feels boomy, foam is addressing the wrong part of the spectrum. You can check any material yourself in our absorption coefficient table.
Panels control reflections inside a room. They do not stop sound getting in or out — that is soundproofing, which means mass and sealing, and no amount of wall panelling substitutes for it.
They also can't fully fix low frequencies. Notice that the 125 Hz column usually stays above target even after treatment. Bass needs either much greater depth or dedicated corner traps, because a thin absorber simply isn't big enough to interact with a wave several metres long.
This calculator estimates from materials, which means it's only as good as your description of the room. If you would rather measure what your room is actually doing, the studio sound check works out your reverberation time from a ten-second recording of your voice.