How many acoustic panels do I need? A simple method for any room

This is the question we hear most often. The answer depends on three things: how big the room is, what is already in it, and what you use it for. Below is a simple method that gives a good result in most homes, a few ready-made examples, and some pointers on when it is worth calculating more carefully.

The floor-area rule

The simplest starting point is the floor area in square metres. Take it and work out how many square metres of panels you need:

• work, video calls, study – a total panel area of about 25–35% of the floor area, 5 cm thick,
• living room, bedroom, dining room – about 15–25%, because these rooms usually have more textiles and do not need to sound as dry, 5 cm thick,
• voice recording, podcasts, home cinema – about 40–60% of the floor area, 10 cm thick.

One 60 × 120 cm panel is 0.72 m². Divide the result by 0.72 and round up. A 12 m² room for work: 30% is 3.6 m², so five 60 × 120 cm panels. The same room for recording: 50% is 6 m², so eight or nine 10 cm panels.

The rule assumes an ordinary furnished room about 2.6 m high – with a bed or sofa, a wardrobe, a few shelves and curtains. If the room is empty, with a hard floor and large windows, you need more. If it has a thick rug, a full bookcase and upholstered furniture, you need fewer.

Where the numbers come from

Behind the rule is reverberation time, RT60: the time it takes a sound to fade by 60 dB once the source stops. In a furnished room it is usually about half a second; in an empty one often more than a second. For talking and working it is good to get down to about 0.4 s, a living room is fine at 0.5 s, recording benefits from 0.3 s, and a home cinema from about 0.35 s.

Reverberation time can be estimated with Sabine's formula: it depends on the room's volume and on how much sound its surfaces absorb. Every square metre of panel absorbs almost all of the sound in the speech range, while a square metre of bare wall reflects most of it. Run the numbers for typical rooms and you get the proportions above. You can see the result for your own dimensions in the calculator below.

It is an estimate, not a measurement. The formula assumes sound spreads evenly through the room, which small rooms do not quite do. Even so, at home it gives a sensible starting point – and from there, where the panels go matters far more than one panel more or less.

Examples for typical rooms

These sets follow from the rule and from our guides for individual rooms:

• Home office, 9–10 m² – 3–5 panels of 60 × 120 cm, 5 cm thick: two behind the monitor, one or two behind you and perhaps one at the side.
• Home office, 12–14 m² – 5–6 panels of 60 × 120 cm: in front of you, behind you and on the side walls.
• Bedroom, 12–15 m² – 3–4 panels. The bed, bedding and curtains already absorb a lot, so panels on two walls are enough.
• Living room, 20–25 m² – 4–6 panels of 80 × 100 cm, for example three above the sofa and one to three by the table.
• Open-plan living room with kitchen, 30–40 m² – 6–10 panels spread over two or three walls.
• Voice-over corner at a desk – 3–4 10 cm panels around the recording spot; here the spot matters more than the whole room.
• Podcast room, 10–12 m² – 6–8 10 cm panels.
• Dedicated cinema room, 12–16 m² – 8–10 10 cm panels plus bass traps in the corners.

We describe placement in detail in our guides to the home office, living room, voice recording and home cinema.

What changes the result

Ceiling height. The rule assumes about 2.6 m. In a room with a ceiling of 3 m or more – a period apartment, or an attic open to the rafters – the volume grows and you need proportionally more panels, roughly 15–25% more for every extra 40 cm of height.

Hard surfaces. Large windows, tiles, concrete, glass and lacquered floorboards reflect nearly all sound. An empty, hard room can need twice as many panels as a furnished one. Before buying more panels, see whether you can add a rug or curtains – that is the cheaper part of the job.

Soft furniture. A sofa, a bed, a thick rug and a bookcase absorb or scatter a good deal of sound. In a well-furnished living room the lower end of the rule is often enough.

Panel thickness. In the speech range, 5 and 10 cm panels absorb practically the same, so for talking and working the number of panels does not change. The difference is in the low frequencies – more on that in 5 or 10 cm.

Don't overdo it

You can have too many panels. A room whose reverberation drops well below 0.3 s sounds dead and tiring – voices feel flat and conversation unnatural. A living room or bedroom has no need to go below 0.5 s. It is better to start with fewer panels in the most important places, listen to the result and add more, than to cover half a wall straight away.

The number is only half of it anyway. Five panels on the first reflection points do more than eight hung wherever there happened to be space. How to find those points is covered in the guide to panel placement.

Large panels or more small ones

What counts is the total area, not the number of pieces. Two 60 × 120 cm panels and one 120 × 120 cm panel absorb about the same. Larger panels are quicker to hang and look calmer. Smaller ones are easier to place exactly on reflection points and to fit around furniture, pictures and sockets.

In practice a mix works well: larger panels on big empty walls, smaller ones where you need to hit a particular spot – behind the monitor, by the microphone, between windows.

When to calculate more carefully

The rule is enough for most homes. It is worth working it out more carefully, or asking us, when:

• the room has an unusual shape, sloping ceilings or opens onto other rooms,
• what bothers you most is booming bass rather than echo,
• you are preparing a room for professional recording or critical listening.

You can use our calculator, or send us photos and the dimensions of your room – with our free advice we will suggest how many panels you need and where to hang them. Just remember that panels improve the sound inside a room and will not soundproof it from the neighbours; we explain the difference in soundproofing vs acoustic treatment.