The electricity price we use
Every cost on this page uses 26.32p per kWh, the average electricity unit rate under the Ofgem price cap for 1 October to 31 December 2026 for people paying by Direct Debit in England, Scotland and Wales. Your own rate depends on your region, how you pay and your tariff, so swap in the figure from your bill if it differs.
The cap from July to September 2026 was 26.11p per kWh. Ofgem notes there is no VAT on electricity from 1 October 2026 to 31 March 2027, so the 2 figures can't be compared like for like. We use the one in force today.
We leave out the standing charge, 54.83p a day under the current cap, because you pay it whether the sauna runs or not. The cap figures cover England, Scotland and Wales; in Northern Ireland, use the unit rate on your bill.
How to work out what a sauna costs per session
An electric sauna heater draws its full rated power while it brings the room up to temperature. After that, a thermostat switches it on and off to hold the heat, so a session has 2 parts, and each is power multiplied by time.
| Step | Sum | 6kW example |
|---|---|---|
| Heat-up energy | Heater kW × hours to reach temperature | 6 × 1 = 6kWh |
| Holding energy | Heater kW × hours in use × share of time the heater is on | 6 × 1 × 0.5 = 3kWh |
| Total energy | Heat-up + holding | 6 + 3 = 9kWh |
| Cost | Total kWh × unit rate | 9 × 26.32p = £2.37 |
For heat-up we use 1 hour. Harvia's Vega manual says a properly insulated sauna takes about an hour to reach bathing temperature when the heater suits the room, and Finnmark's outdoor sauna manual tells owners to allow at least an hour.
The holding share is our assumption, not a manufacturer figure. We use 50%, meaning the heater is on for half of each hour once the room is hot. Thick walls, a still night and a closed door push it lower; thin walls, wind and a door that keeps opening push it higher.
How much a 3.5kW, 6kW, 8kW and 9kW sauna costs per session
These are the common electric heater sizes for home saunas. Each row uses a 1-hour heat-up and a 1-hour session with the heater on half the time, at 26.32p per kWh.
| Heater | Room it suits | Heat-up | Holding | Total | Cost per session |
|---|---|---|---|---|---|
| 3.5kW | 2–4.5m³ | 3.5kWh | 1.75kWh | 5.25kWh | £1.38 |
| 6kW | 5–8m³ | 6kWh | 3kWh | 9kWh | £2.37 |
| 8kW | 7–12m³ | 8kWh | 4kWh | 12kWh | £3.16 |
| 9kW | 8–14m³ | 9kWh | 4.5kWh | 13.5kWh | £3.55 |
The room volumes are Harvia's ratings for its Vega heaters, and they explain why the bigger cabins cost more to run: a bigger room needs a bigger heater to reach temperature in the same hour. Harvia ties the 1-hour heat-up to a heater that suits the room, so an undersized heater runs flat out for longer and costs more than the table shows.
Heater size moves the bill more than brand does, so compare the room volume each of the best electric sauna heaters is rated for against your cabin before you compare prices. At the July to September cap of 26.11p, the same 6kW session was £2.35, so the new cap adds about 2p.
A bigger heater also needs a bigger circuit, so weigh the electrical requirements for each heater size alongside the running cost when you choose between a 6kW and a 9kW cabin.
How much an infrared sauna costs per session
Infrared cabins use heating panels rated in watts instead of a heater full of stones, and they draw much less. A panel can't draw more than its rating, so an hour at full power is the ceiling for an hour in the cabin, warm-up included.
Clearlight's UK listings show where real cabins sit: 2,160W for its 1-person Sanctuary, 2,500W for the 2-person and 3,560W for the 5-person outdoor cabin. The 1.6kW row is an example of a smaller 1-person cabin.
| Infrared cabin | Energy in 1 hour at full power | Most it costs per hour |
|---|---|---|
| 1.6kW, small 1-person | 1.6kWh | 42p |
| 2.16kW, 1-person | 2.16kWh | 57p |
| 2.5kW, 2-person | 2.5kWh | 66p |
| 3.56kW, 5-person outdoor | 3.56kWh | 94p |
If your cabin's controller cuts the panels back once the air reaches the set temperature, a session costs less than this. Treat the table as the most an hour can cost, not the typical figure.
Running cost is one of the clearer gaps between infrared and traditional saunas: a 2.5kW cabin costs under a third of a 6kW heater's session. They don't heat you the same way, so cost is only part of that choice.
Yearly running costs at 1, 3 and 7 sessions a week
Each figure below is the cost per session multiplied by sessions a year (52, 156 or 364), at 26.32p per kWh all year. Ofgem resets the cap every quarter, so read these as today's rate carried forward, not a forecast.
| Heater | 1 a week | 3 a week | 7 a week |
|---|---|---|---|
| 3.5kW electric | £72 | £216 | £503 |
| 6kW electric | £123 | £370 | £862 |
| 8kW electric | £164 | £493 | £1,150 |
| 9kW electric | £185 | £554 | £1,293 |
| 2.5kW infrared | £34 | £103 | £240 |
Daily use on a 9kW heater costs more than £1,200 a year at today's rate. If you plan to use the sauna every day and rarely have more than 2 people in it, a smaller cabin with a 3.5kW or 6kW heater saves £400 to £800 a year on the same habit.
The yearly totals here use the typical session. Outdoor saunas used mostly in winter will land above them, and indoor saunas in a heated house nearer the mild figures in the next section.
Why an outdoor sauna costs more to run in winter
On a cold night, 2 things change. The cabin starts colder, so the heat-up runs longer at full power, and the walls lose heat faster, so the thermostat keeps the heater on for more of each hour.
| 6kW heater, 1-hour session | Heat-up | Heater on while holding | Total | Cost |
|---|---|---|---|---|
| Mild evening | 45 minutes | 35% | 6.6kWh | £1.74 |
| Typical | 1 hour | 50% | 9kWh | £2.37 |
| Cold winter night | 1.5 hours | 70% | 13.2kWh | £3.47 |
The mild and cold rows are illustrations built on our own assumptions, not measured figures. They show the spread: the same 6kW cabin can cost under £2 or close to £3.50 for the same hour on the bench.
Wall build is the part of this you choose. Thicker, better-sealed walls lose heat more slowly, so the heater spends less of each hour switched on, and that saving repeats every session for the life of the cabin. A sauna inside a heated house starts warmer and loses less heat, so it sits nearer the mild row all year.
Wall thickness and build vary widely between garden cabins, so check the wall spec before you buy if you'll use yours mainly from October to March. Checking costs nothing, and the difference shows up on every winter bill.
How much a wood-fired sauna costs to run
A wood-burning sauna heater uses no electricity, so its running cost is the logs. How much a session burns depends on the stove, the cabin, the weather and how hard you fire it, so the reliable way to price it is per volume of logs, then count what you use.
As a worked example, Certainly Wood's kiln-dried ash crates cost £345 for 1.42m³, £470 for 2.29m³ and £599 for 3.08m³ on its own site today.
| Crate | Volume | Price | Per m³ | Per 10 litres |
|---|---|---|---|---|
| Medium | 1.42m³ | £345 | £243 | £2.43 |
| Large | 2.29m³ | £470 | £205 | £2.05 |
| Extra large | 3.08m³ | £599 | £194 | £1.94 |
A cubic metre is 1,000 litres, so divide the price per m³ by 100 for the cost of 10 litres. Fill a basket of known size for your first few sessions, note how many you burn, and you have your cost per session.
Check whether you live in a smoke control area before you buy a wood-fired cabin. The smoke control rules say wood can only be burned there in an exempt appliance, and in England a smoking chimney can bring a penalty of up to £300.
Sauna habits that change the running cost
The heater's timer is the biggest one. On Harvia's Vega, turning the timer to "on" runs the heater for up to 4 hours, and the pre-set setting starts it up to 8 hours later and then runs it for about 4 hours, according to the same Vega manual. Leave a 6kW heater holding for 2 extra hours after you've finished and that's 6 × 2 × 0.5 = 6kWh, or about £1.58 on top of the session.
Use the pre-set the other way round: time the heat-up so the room reaches temperature as you arrive, not an hour before. Harvia also says it can be worth leaving the heater on for a while after bathing so the wood dries, or you can leave the door open instead; 15 minutes of a 6kW heater at half duty is 0.75kWh, about 20p.
| Habit, 6kW heater | Extra energy | Extra cost |
|---|---|---|
| Heater left holding 2 hours after the session | 6kWh | £1.58 |
| Heat-up started 1 hour too early, then holding | 3kWh | 79p |
| 15 minutes left on to dry the wood | 0.75kWh | 20p |
The number of people in the cabin barely changes the bill, because the heater's power doesn't change with who's sitting there. With 4 people in a 6kW session it's about 59p each; a person on their own pays the full £2.37.
How to measure your own sauna's running cost
A smart meter's in-home display gives you the real number in a single session. Note the kWh reading when you switch the heater on and again when you switch it off, then multiply the difference by your unit rate.
Do it with nothing else big running, such as an oven, a tumble dryer or an electric car on charge, or the reading will include them. Repeat it on a mild night and a cold one and you have your own version of the winter table above.
If you're on a multi-rate tariff such as Economy 7, you pay one unit rate at peak times and another off-peak. Use the rate for the hours you actually use the sauna, which may not be the one on the front of your bill.
Questions people ask
How much does it cost to run a sauna in the UK?
About £2.37 a session for a 6kW electric sauna at the Ofgem cap of 26.32p per kWh for October to December 2026, assuming a 1-hour heat-up and a 1-hour session. A 3.5kW heater costs about £1.38 and a 9kW about £3.55 on the same basis. A 2.5kW infrared cabin costs no more than 66p an hour.
How many kWh does a 6kW sauna use?
About 9kWh for a typical session: 6kWh to heat up over an hour, then about 3kWh to hold temperature for an hour with the heater on half the time. On a cold winter night that can rise to around 13kWh.
Is an infrared sauna cheaper to run than a traditional sauna?
Yes, it costs under a third as much per session. A 2.5kW infrared cabin costs at most 66p for an hour at the current cap, against about £2.37 for a 6kW traditional sauna with its 1-hour heat-up. The 2 types heat you differently, so running cost is only part of the choice.
Does a sauna use more electricity in winter?
Yes, especially outdoors. A colder cabin takes longer to heat and the thermostat keeps the heater on for more of each hour, so the same 6kW session can go from about £2.37 to around £3.47 on a cold night. An indoor sauna in a heated house changes much less.
Is it cheaper to run a sauna on Economy 7?
Only if you use it in the off-peak hours. On a multi-rate tariff you pay one unit rate at peak times and another off-peak, so a session costs whichever rate applies when it runs. Check the hours and both rates on your bill and put the right one into the sum.