Sauna running costs UK 2026: cost per session at the current price cap
How much electricity a home sauna uses per session, worked out for 1.9kW infrared cabins up to 9kW heaters at the Ofgem cap of 26.32p per kWh, with every assumption shown.
Quick answer
At the Ofgem price cap of 26.32p per kWh (October–December 2026), a typical 6kW electric sauna costs about £2.17 per session on our assumptions: an hour's warm-up at full power plus a 45-minute session with the heater on half the time. That's about £340 a year at three sessions a week. A 1.9kW plug-in infrared cabin costs about 30p a session on similar assumptions, or about £47 a year. Your real cost depends mostly on warm-up time, insulation and how hot you like it.
Running cost is simple arithmetic: power (kW) × hours on × price per kWh. The hard part is knowing how long the heater is actually on. This guide sets out the assumptions, shows the numbers for common heater sizes, and checks them against the retailers’ own estimates.
Our assumptions
| Assumption | Value we use | Why |
|---|---|---|
| Electricity price | 26.32p per kWh | Ofgem price cap, Direct Debit, GB average, 1 October to 31 December 2026 (no VAT on electricity this period) |
| Warm-up, traditional | 60 minutes at full power | Harvia’s manual: about an hour for a properly insulated sauna with a correctly sized heater |
| Session, traditional | 45 minutes | Our assumption for a typical session |
| Heater duty once hot | 50% | Our assumption. The thermostat cycles the heater; we haven’t measured this |
| Warm-up and session, infrared | 15 minutes, then 30 minutes at 70% | Our assumption |
| Sessions | 3 a week, 52 weeks | Our assumption |
Change any of these
The sauna cost calculator uses exactly this method and lets you change every figure, including your own unit rate from your bill.
Cost per session by heater size
Energy per session = kW × 1 hour warm-up + kW × 0.75 hours × 50%. That works out at 1.375 × the heater’s kW.
| Heater | kWh per session | Per session | Per year (3 a week) |
|---|---|---|---|
| 3.5kW (e.g. Polar Sauna Cube Mini) | 4.8 | £1.27 | £198 |
| 4.5kW (e.g. SaunaPlunge Brontë) | 6.2 | £1.63 | £254 |
| 6kW (e.g. Polar Sauna Cube, Pennine 4) | 8.3 | £2.17 | £339 |
| 8kW (e.g. Pennine 6) | 11.0 | £2.90 | £452 |
| 9kW (e.g. Holl’s Orphée) | 12.4 | £3.26 | £508 |
| 1.9kW infrared (e.g. Kajo 2) | 1.1 | £0.30 | £47 |
Figures are rounded. The table assumes the same one-hour warm-up for every heater size. In reality warm-up time depends on the room size, insulation and weather as much as on the heater, so treat these as a guide rather than a prediction.
How this compares with the retailers’ figures
- Steam & Oak, Prism (6kW): “typically £1.75–£2.25 per 90-minute session” at 30p/kWh, which implies roughly 5.8–7.5kWh. Our method gives 7.5kWh for 90 minutes (60 minutes warm-up plus 30 minutes at 50%), at the top of their range.
- Steam & Oak, Kajo 2 (1,900W infrared): “about 25p for a 30-minute session” at the July–September 2026 cap, with the thermostat keeping real use below that worst case.
Both are the retailers’ estimates, not independent measurements, but they’re in the same range as ours.
What makes a sauna cost more or less to run
- Warm-up time. The largest single use. Insulated cabins and correctly sized heaters warm up faster. Bare-stave barrels lose more heat in winter.
- Target temperature. Every degree hotter means more time with the heater on.
- Weather. Heating from 2°C in January takes longer than from 18°C in June.
- Your tariff. On a time-of-use tariff, heating at cheaper times can cut the cost. Use your actual unit rate.
- Door discipline. Every time the door is opened, hot air escapes and the heater works harder.
Wood and gas
Wood-fired and gas heaters avoid electricity costs but have running costs of their own: logs or bottled propane. We haven’t found reliable published consumption figures for the heaters in our guides, so we don’t estimate them here. If you’re considering wood, check whether you’re in a smoke control area first.
Measuring your own
A hard-wired sauna heater can’t go through a plug-in energy monitor. If you have a smart meter, the in-home display or your supplier’s app will show the jump in usage while the sauna is heating. Note the reading before and after a session for a real figure.
Frequently asked questions
How much does it cost to run a sauna for an hour in the UK?
A heater running flat out uses its rated power every hour: 6kWh for a 6kW heater, which costs about £1.58 at 26.32p per kWh. Once the room is hot, the thermostat switches the heater on and off, so an hour of bathing usually costs less than that. The warm-up is the expensive part.
Is an infrared sauna cheaper to run than a traditional sauna?
Usually, because infrared cabins use smaller heaters (about 1.2–2.6kW for the cabins we've listed, against 4.5–9kW for traditional heaters) and need less warm-up time. On our assumptions, a 1.9kW infrared session costs about 30p against about £2.17 for a 6kW traditional sauna.
How long does a sauna take to heat up?
Harvia's heater manual says a properly insulated sauna with a correctly sized heater takes about an hour to reach bathing temperature. Uninsulated barrels and cold weather can take longer. Infrared cabins are usually ready sooner because they don't need to heat the air as much.
Does the standing charge count towards sauna running costs?
No. You pay the daily standing charge (54.83p a day on the cap for October–December 2026) whether or not you use the sauna, so it isn't an extra cost of running it.
Sources
We read each of these on or before 10 November 2026. Retailer links in this list are plain links, not affiliate links.