Echo calculator: How many acoustic panels does your room need?
Tell us about your room. We’ll estimate its echo time (how long a clap takes to fade away), work out how many wall panels bring it down to a comfortable level for that kind of room, and let you hear the difference.
Your room rings for about 0.70 seconds. Aim for 0.6. With 1 panel it drops to about 0.58.
1 full-size panel (1200 × 2800 mm), trimmed to your 2.7 m ceiling, brings your echo time down to about 0.58 s.
- Panel area to reach 0.6 s2.6 m²
- One panel covers3.24 m² (1.2 × 2.7 m)
- Echo time with panels0.58 s
- Each$418.00 · 12 mm
How fast a clap dies away
This is an estimate using Sabine’s formula and published average absorption figures. Furniture, rugs and curtains soak up extra sound, so a furnished room may already be a bit better. Panel rating: NRC 0.85 (supplier data). How we work it out ↓
How we work it out
In plain words
Clap in a room and the sound doesn’t stop straight away. It bounces off the walls, floor and ceiling, and at every bounce a little of it gets soaked up. Soft things like carpet, people and felt panels soak up a lot. Hard things like glass, concrete and plasterboard bounce most of it back.
The echo time is how long the clap takes to die away. Sound experts call it reverberation time, or RT60: the time it takes a sound to drop by 60 decibels, which is one millionth of its energy.
Echo time = 0.161 × V ÷ AV is the room’s volume (length × width × height, in m³). A is how much sound the room soaks up (in m²).
To get A, we take each surface’s area, times its absorption number (0 soaks up nothing, 1 soaks up everything), add them all up, then add 0.435 m² for each person. This is Sabine’s formula.
Then we work out how much more soaking-up the room needs to hit the target. Acouline panels are rated NRC 0.85, so they soak up about 85% of the sound that hits them. A panel covers wall that was already soaking up a little, so each square metre of panel adds 0.85 minus that wall’s own number.
One full-size panel is 1200 × 2800 mm. In a room lower than 2.8 m it’s trimmed to the ceiling, so it covers 1.2 m × your ceiling height. We round up to whole panels, and we keep 1.7 m² of wall free for a door.
The numbers we use
| Surface | Absorption |
|---|---|
| Floor | |
| CarpetCarpet, thin, over thin felt on concrete | 0.25 |
| TimberWooden floor on joists | 0.085 |
| TilesCeramic tiles with smooth surface | 0.015 |
| Vinyl / linoLinoleum or vinyl stuck to concrete | 0.0325 |
| Polished concreteSmooth unpainted concrete | 0.0175 |
| Walls | |
| PlasterboardPlasterboard on frame, 100 mm airspace | 0.08 |
| Brick / blockSmooth brickwork with flush pointing | 0.0375 |
| ConcreteSmooth concrete, painted or glazed | 0.015 |
| Glass and windows6 mm glass | 0.0375 |
| Ceiling | |
| PlasterboardPlasterboard on frame, 100 mm airspace | 0.08 |
| ConcreteSmooth concrete, painted or glazed | 0.015 |
| Acoustic ceiling tilesMineral wool tiles, 180 mm airspace | 0.83 |
| People and panels | |
| Each personAdults, seated | 0.435 m² |
| Acouline wall panelSupplier rating, 12 mm and 24 mm | NRC 0.85 |
The targets, and where they come from
- Open-plan office: 0.5 s. The WELL Building Standard (feature 78) asks for 0.5 s or less in open workspaces.
- Meeting / board room: 0.6 s. The WELL Building Standard (feature 78) asks for 0.6 s or less in conference rooms.
- Classroom / training room: 0.6 s. The WELL Building Standard (feature 78) asks for under 0.6 s in learning spaces up to 3,000 m³.
- Home office / study: 0.6 s. Our pick: the same as a meeting room.
- Living / media room: 0.6 s. Our pick: the same as a meeting room.
- Café / restaurant: 0.8 s. The middle of the 0.6–1.0 s range AS/NZS 2107 gives for bars and lounges, as reported by the Australian Acoustical Society.
- Podcast / voice booth: 0.3 s. The middle of the 0.2–0.4 s range AS/NZS 2107 gives for a voice-over booth, as reported by the Australian Acoustical Society.
These targets are a guide to a comfortable room. This calculator doesn’t check or certify that a room meets any standard.
Sources
- Table of sound absorption coefficients (PDF): the figures for floors, walls, glass, ceilings and people.
- WELL Building Standard, feature 78: Reverberation time: open workspaces, conference rooms and learning spaces.
- Burgess and Gabriels, “Overview of the revision of AS/NZS 2107”, Australian Acoustical Society (PDF): bars and lounges, and voice-over booths.
- Acouline panel rating, NRC 0.85: our supplier’s product data.
Questions people ask
What is echo time (reverberation time)?
It’s how long a sound hangs around in a room after it stops. Clap once and listen: the time the clap takes to fade away is the echo time. Sound experts call it reverberation time, or RT60, the time it takes a sound to drop by 60 decibels. A shorter echo time usually means clearer speech and a calmer room. The WELL Building Standard asks for 0.6 seconds or less in meeting rooms.
How many acoustic panels does a meeting room need?
It depends on the room’s size and what it’s made of. Take a 5 × 4 m meeting room with a 2.7 m ceiling, carpet, plasterboard walls, 30% glass and six people. It works out at about 0.7 seconds, and one full-size 1200 × 2800 mm panel brings it under the target of 0.6 seconds. With a vinyl floor instead of carpet, the same room is closer to 1.1 seconds and needs about three panels. Put your own room into the calculator above to get your number.
Will acoustic panels stop noise going through the walls?
No. Panels soak up sound inside the room, so they cut the echo and make voices clearer. They don’t soundproof a wall. Stopping sound getting from one room to the next depends on how the walls, ceiling and doors are built and sealed, not on what’s hung on them.
Should I choose 12 mm or 24 mm panels?
Our supplier rates both thicknesses NRC 0.85, so this calculator treats them the same. Choose on look, feel and budget: the 24 mm panel is thicker and costs more.
Where should I put the panels?
The formula only counts how much panel you add, not where it goes, but placement still helps in a real room. Spread the panels around rather than bunching them in one corner, put them at the height where people sit and talk, and start with bare walls that face each other or face a window. If your walls are mostly glass, the ceiling is the next place to look.
How accurate is this calculator?
It’s an estimate, not a measurement. It uses Sabine’s formula and published average absorption figures for each surface. Furniture, rugs, curtains and bookshelves soak up extra sound, so a furnished room may already be a bit better than the number shown. For a recording studio, a lecture theatre or anything critical, have an acoustic consultant measure the room.