Barrel sauna capacity: what "seats four" means
Every barrel sauna is sold with a number of people in the title. It is the first thing you see and the first thing you compare, and it is the least comparable number on the page.
Here is what it is actually made of, and what to compare instead.
The figure is a judgement, not a measurement
Nobody tests a capacity claim. There is no standard for it, no test rig, and no body that checks. A capacity figure is somebody deciding how many adults will sit on a bench without minding.
That decision is made differently across factories, and you can watch it happen in our own range. We sell two lines of barrel sauna, and this is how much bench each gives per seat.
| Model | Steam room | Bench run | Seated | Lying down | Bench per seat |
|---|---|---|---|---|---|
| Anita S | 1.6 m | 4.1 m | 4 | 2 | 1.0 m |
| Anita M | 1.6 m | 3.2 m | 4 | 2 | 0.8 m |
| Anita L | 2.1 m | 4.0 m | 4 | 2 | 1.0 m |
| Barrel Sauna S | 2.0 m | 3.6 m | 4 | 2 | 0.9 m |
| Barrel Sauna M | 2.5 m | 4.6 m | 6 | 2 | 0.8 m |
| Barrel Sauna XL | 3.0 m | 5.6 m | 8 | 2 to 4 | 0.7 m |
Bench run is measured along every bench in the room, top and bottom. The Anita S is laid out differently from the rest: its benches run across the barrel rather than down the sides, on two levels. Across a barrel the curved wall closes in at both ends of every bench, so four is the most that fit across 2 levels.
The last column is the one that matters. Across one shop, selling one product type, the bench allowed per seated person runs from 0.7 m to 1 m, close to half as much bench again for one seat as for another. The same word, four, is printed against 3.2 m of bench and against 4.1 m.
What the number is measuring, when it measures anything
Most barrels have a bench down each side, running the length of the room. Our 2 m Barrel Sauna S has 3.6 m of bench. At shoulder width that is seven people, and it is sold as four, which tells you the constraint is somewhere other than shoulders.
It is knees. Two benches face each other across a metre or so of aisle, and four people cannot all put their legs down at once. Add the heater, which stands between the benches at the far end and needs a clearance around it, and the door, which cannot open into someone. That is why most of our barrels carry less bench than twice their length. What is left is judgement, and different people judge it differently.
The lying figure behaves differently. Lying is set by the benches, one person to a bench, and every barrel here has two. From about 1.6 m of bench an adult reclines comfortably. Stretching out completely flat takes closer to 1.8 m.
More than two people can only lie down when each bench is long enough to take two. Our 3 m Barrel Sauna XL lies two stretched out flat, one to a side, or four propped up Roman style, two to a side. Short of that, extra length buys a full stretch, elbow room and more people sitting up, not another person lying down.
The two columns behave differently. Lying follows the benches. Seated wanders, because it is an opinion about how close your friends will sit.
This is about barrels
Everything above is barrel geometry: two benches, both the length of the room, facing each other.
A cabin sauna is laid out differently. Benches run along one or two walls, usually in two tiers, often in an L, and the usable bench depends on where the door and the heater land rather than on the length of the room. None of the per-metre figures on this page transfer to a cabin, and we are not going to pretend they do.
The same claim, at very different sizes
Our own range is only half the picture. You are not choosing between two of ours, you are choosing across the market, and the same word is doing very different work out there.
Three barrel saunas on sale in Australia in September 2026, described only by what each listing publishes about itself. Prices are the regular price, not a sale price.
| Advertised as | Barrel length | Diameter | Heater | Price |
|---|---|---|---|---|
| "Up to six adults" | 2.3 m | 1.9 m | 6 kW, included | $11,995 |
| "4 to 6 person" | 2.8 m | 2.3 m | not included | $15,090 |
| "2 to 4 person" | 1.5 m, benches 1.3 m | 1.8 m | 4.5 kW, included | $8,490 |
The second barrel is half a metre longer than the first and claims fewer people. If capacity were a scale, that could not happen. It happens because the two sellers made different judgements about how close six adults will sit, and both wrote down what they judged.
The third row is the one to sit with. Benches of 1.3 m, in a room 1.5 m long, too short to recline on. It is sold as up to four, and four is defensible for four people sitting upright and still. It is not the sauna most people picture when they read four.
None of these listings is dishonest. Each is a reasonable person describing their own product. That is exactly why the number cannot be compared across sellers.
Three divisions that make listings comparable
Capacity on its own tells you nothing. Capacity divided by something real tells you plenty.
Metres of room per claimed person is always available. At about 0.4 m or less the claimed number is a maximum: everyone upright, everyone still. Around 0.5 m it is the number that can comfortably use the room at once. That is the difference between a sauna you can fit six into and a sauna for six.
Cubic metres per claimed person is better, because it sees the diameter. Length alone treats a 1.8 m barrel and a 2.3 m one as the same purchase. Volume rises with the square of the radius, so width does far more to a room than length. Around 1 m³ each is a full room. Around 2 m³ is room to sit apart and stay a while. A heater is sized on a related but smaller figure, the air inside the room, which sizing a sauna heater works through.
Dollars per cubic metre answers the question you arrived with. Three rules keep it fair. Use the room and not the barrel. Use the regular price, not a sale price: a discount ends, the sauna does not, and a sale can move a barrel from the bottom of this table to the top for a few weeks. And add a heater where one is not included. We have used $1,400, which is what a basic sauna heater with stones costs, applied to both sides so it lands on our own kits too.
All three, on the eight listings, rounded:
| Room | Volume | Claimed | m per person | m³ per person | With heater | Per m³ | |
|---|---|---|---|---|---|---|---|
| Our Anita L | 2.1 m, Ø2.2 | 7.9 m³ | 4 | 0.5 | 2.0 | $10,450 | $1,300 |
| Our Anita M | 1.6 m, Ø2.2 | 6.3 m³ | 4 | 0.4 | 1.6 | $9,130 | $1,450 |
| Our Barrel Sauna XL | 3.0 m, Ø1.9 | 8.5 m³ | 8 | 0.4 | 1.1 | $12,500 | $1,450 |
| Our Barrel Sauna M | 2.5 m, Ø1.9 | 7.1 m³ | 6 | 0.4 | 1.2 | $10,900 | $1,550 |
| Our Barrel Sauna S | 2.0 m, Ø1.9 | 5.7 m³ | 4 | 0.5 | 1.4 | $10,500 | $1,850 |
| "Up to six adults" | 2.3 m, Ø1.9 | 6.5 m³ | 6 | 0.4 | 1.1 | $11,995 | $1,850 |
| "4 to 6 person" | 2.1 m, Ø2.3 | 8.7 m³ | 6 | 0.4 | 1.5 | $16,490 | $1,900 |
| "2 to 4 person" | 1.4 m, Ø1.8 | 3.6 m³ | 4 | 0.4 | 0.9 | $8,490 | $2,400 |
On regular prices our own barrels take the top four places. That is what the arithmetic gives, and it is why the method and every input are printed here: none of it needs taking on trust.
Two rows are worth reading twice.
The dearest listing is not the worst value. That $16,490 barrel is the most expensive thing here by nearly four thousand dollars. It is also 2.3 m across and, at 8.7 m³, the largest sauna in the table, and per cubic metre it costs less than a barrel that is eight thousand dollars cheaper. Expensive and poor value are different accusations.
The cheapest has the dearest air. At 1.8 m across and 1.4 m of room it is 3.6 m³, less than half the sauna of the row above, and its benches are 1.3 m, too short to recline on. Sticker price sorts that pair exactly backwards.
Our own Anita M makes the same point in reverse. Sixth of eight on price per metre, second on price per cubic metre. Nothing about the sauna changed. Only one of those columns can see that it is 2.2 m across.
Where the volumes come from. Room volume values are not typically published across retailers. Every one here is calculated the same way, from the two figures each listing does publish: π r² times the steam room length, on the barrel's outside diameter. It counts the timber as well as the air, which is what the price buys. Heating is the other question, and it runs on the air alone, which is the smaller figure the heater article works from.
Small saunas cost more per cubic metre. All of them.
Two end walls, a door, a heater, a roof, cradles and a pallet of freight. None of those get cheaper when the barrel gets shorter, and the volume does. Our own range shows it twice, in two product lines built to different specifications:
| Volume | Per m³ | |
|---|---|---|
| Barrel Sauna S | 5.1 m³ | $2,050 |
| Barrel Sauna M | 6.4 m³ | $1,700 |
| Barrel Sauna XL | 7.7 m³ | $1,600 |
| Anita M | 5.8 m³ | $1,600 |
| Anita L | 7.3 m³ | $1,450 |
Same timber, same wall, length the only variable. Volume is the right comparison there, between like sizes. A 3 m³ barrel will always look dear beside an 8 m³ one, and that tells you nothing about either.
It does answer the question people ask us most: is it worth going a size up? On the purchase price, the extra metre is the cheapest volume you will buy. It is not free to run. More volume needs a bigger heater, which costs more to buy and more to heat every session, and past about 8 m³ it can mean three-phase power once the air inside passes about 8 m³. The sauna is worth sizing for the people who will use it, not for the price per cubic metre.
What the volume figure cannot see
It ranks on space bought and is blind to everything else. Two of those are worth real money.
Stave thickness, which is the insulation. The staves are the curved side wall and two-thirds to three-quarters of the enclosing surface, so they are the number that matters. End walls are thinner and count for less.
| Staves | |
|---|---|
| Our Barrel Sauna S, M and XL | 58 mm |
| Our Anita range | 42 mm |
| "4 to 6 person" | 42 mm |
| "2 to 4 person" | 38 mm |
| "Up to six adults" | not stated |
Half as much timber again between you and an Australian winter, invisible in a price per cubic metre, and visible on every power bill for as long as you own it. One of the four does not publish it at all.
What is actually in the crate, which is where two barrels at the same price stop being the same purchase. Roof covering or bare roof. Cradles in treated timber, untreated timber or plastic, which are three different lifespans on Australian ground. Glazing, from a timber door to a full glass wall, which is a large part of the cost and most of how it feels inside. Stones, without which a heater does not work. Freight, in the price or added at checkout.
Accessory bundles belong here too: our Barrel Sauna S, M and XL arrive with lights, stones, bucket, thermometer, backrests and head rests included. A bundle is worth pricing once and setting aside. A generous one is a few hundred dollars at retail, and it never closes a four-figure gap.
What to ask before you buy
Ten questions to ask the seller:
- What is the length of the steam room, inside, excluding any porch or changing room?
- What is the volume of the steam room in cubic metres? This one also sizes your heater. Few listings publish it. Ask.
- How long is the bench? Under about 1.6 m nobody reclines comfortably, and under about 1.8 m nobody stretches out flat.
- How thick are the staves? This is the insulation.
- What timber is it?
- Is the heater included, and at what kW?
- Is freight included or extra?
- What is the price with roof covering, stones and cradles?
- What is in the accessory bundle, and what would it cost to buy separately?
- Where is it manufactured, and what does "designed" cover?
The three divisions are then worth running: length over people, volume over people, and price over volume. A minute's arithmetic, and the shortlist usually sorts itself.
We publish steam room length and diameter in the dimension drawing, both capacity figures on the listing, and room volume where we have it. Where a seller publishes no volume, ask for it.
The short version
Capacity is a useful shorthand and a poor comparison. Use it to shortlist, then decide on the numbers under it. Volume per person beats length per person, because it sees the diameter. Neither figure is enough on its own: what the price contains, how thick the staves are and what it costs to heat all move the answer.
Put the questions above to every seller on your shortlist, ours included. The answers decide it, not the number in the title.
