How Much Does It Cost to Run an Outdoor Sauna in the UK?

How Much Does It Cost to Run an Outdoor Sauna in the UK?

A one-hour session in an electric outdoor sauna costs roughly £1.20 to £3.00 to run in the UK, including heat-up. That figure is based on the current Ofgem price cap electricity rate of 26.32p per kWh (October to December 2026), and the biggest factor is the size of your heater.

At two sessions a week, that works out at around £120 to £310 a year. Below, we show how we reached those numbers, so you can get a feel for your own.

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What a sauna session involves

A sauna session has two parts that use electricity: heating the cabin up, then keeping it hot while you use it. Understanding both is the key to an honest running cost figure.

Heat-up. An electric heater typically takes 30 to 45 minutes to bring an outdoor sauna up to bathing temperature. Allow up to an hour on a cold winter evening, or with heaters that hold a large mass of stones. During this stage the heater runs at full power.

Time in use. A traditional session is rarely one long sit. Most people enjoy two or three rounds of 10 to 15 minutes in the heat, with a cool-down in between, so the sauna is kept hot for somewhere between 30 and 90 minutes. Once at temperature, the thermostat switches the heater on and off to hold it steady, so it draws far less than its full rating.

The recommended bathing temperature for most electric heaters is 60 to 80°C.

Cost per session by heater

A one-hour session costs about £1.18 with a 3.6kW heater, £1.97 with a 6kW heater and £2.96 with a 9kW heater. Here's the full picture across shorter and longer sessions.

Heater Typical saunas Kept hot 30 min Kept hot 60 min Kept hot 90 min
3.6kW Tyyni barrels (without glass wall) £0.95 £1.18 £1.42
6kW Löyly, Liekki, Usva, Lagom Four-Person, Tyyni glass wall models £1.58 £1.97 £2.37
9kW Ro and our larger multi-room saunas £2.37 £2.96 £3.55

How we worked it out. Each figure includes a 45-minute heat-up at full power, plus an allowance for the thermostat switching the heater on and off to hold the temperature. We used the Ofgem price cap rate of 26.32p per kWh for October to December 2026. The standing charge isn't included, since you pay it whether or not you use the sauna.

Treat these figures as a helpful guide rather than a fixed price. Real-world running costs vary with your tariff, the weather, the cabin and how often the door opens. The HUUM DROP 6kW, available across our range, sits in the 6kW row.

Narvi NM electric sauna heater in black, available in 6kW and 9kW outputs

Yearly running costs

Two one-hour sessions a week with a 6kW heater cost about £205 a year, or roughly £17 a month. That's the most common setup across our range.

Heater Once a week Twice a week Three times a week
3.6kW £62 £123 £185
6kW £103 £205 £308
9kW £154 £308 £462

All figures assume one-hour sessions at 26.32p per kWh. Ofgem reviews the price cap every three months, so we'll update this table as rates change.

What affects running costs

How well your sauna holds its heat matters more than anything else, because a cabin that retains warmth lets the thermostat rest for longer. These are the factors that make the biggest difference.

  • Wall thickness. Solid timber walls absorb heat and release it slowly. Our saunas use 42mm log walls on the barrel ranges, 44mm on Lagom and 56mm on Ro, while Liekki uses an insulated panel system. Thicker walls mean steadier heat once you're up to temperature.
  • Glass. Glass walls and large windows bring the garden into your sauna, and they lose heat faster than timber. That's why we pair glass wall models with a slightly larger heater, so they still reach temperature comfortably.
  • Outside temperature. A December evening asks more of your heater than a mild spring day, mostly during heat-up.
  • The right heater size. An undersized heater runs flat out for longer and may never quite reach temperature. Every heater we offer is matched to the cabin it comes with.
  • Stones. Heater manufacturers recommend stacking stones loosely so air can circulate. Stones packed too tightly slow down heat-up.
  • The door. Every opening lets heat out, so it pays to keep it closed while the sauna warms up.

Electric vs wood-fired

A wood-fired sauna uses no electricity to heat, so its running cost comes down to how you source your logs. Buy them in, and you'll pay whatever your local supplier charges. Have your own woodland, or already keep a log store for a wood burner in the house, and your sauna can cost very little to run at all.

Electric Wood-fired
What you pay for Electricity, per kWh Logs, bought in or sourced yourself
Heat-up Press a button, or set a timer Light and tend the fire
Temperature control Thermostat holds it steady Managed by how you feed the fire
Power supply Dedicated circuit fitted by a qualified electrician None needed for heating
Best for Convenience and predictable costs Tradition, off-grid gardens, the crackle of a real fire

Our Harvia Wood Burner Set is available on most of our saunas, with the exception of our smallest models (Tyyni Solo, and Usva 1.1m² and 1.4m²), where the cabin is too compact for a wood stove. Many owners choose wood for the ritual as much as the running cost.

Can you run a sauna on solar panels?

Yes, solar panels can cut what you pay to run a sauna, especially in summer. In winter they help less on their own, but paired with a home battery and an off-peak tariff they can make a real difference all year round.

Summer. A south-facing 4kW system in the Midlands generates around 449 kWh in June, roughly 15 kWh a day. A one-hour session with a 6kW heater uses about 7.5 kWh, so a sunny day's generation can comfortably cover an afternoon session.

Winter. The same system produces around 65 kWh in December, about 2 kWh a day. UK panels typically produce 20 to 30% of their summer output through December to February, and most of us sauna after dark. In the colder months, solar alone will cover only part of a session.

Batteries. A home battery lets you store daytime solar for an evening session. Check its maximum power output: some systems deliver 3 to 5kW, while newer units such as the Tesla Powerwall 3 can supply up to 11.5kW continuously. If your battery delivers less than your heater draws, the grid simply tops up the difference.

Off-peak tariffs. This is often the bigger win in winter. Time-of-use and EV tariffs offer overnight electricity from around 6.5p to 9.5p per kWh. Charge a battery overnight and run your session from it, and a 6kW one-hour session could cost nearer 50 to 70p instead of £1.97, allowing for a little energy lost in storage.

Ways to keep running costs down

The simplest saving is timing: switch the heater on so the sauna is ready when you are, not before. A few small habits do the rest.

  1. Use a timer. The Narvi heater's built-in clock switch can preset a start up to 8 hours ahead, and the HUUM DROP can be scheduled from your phone with a Wi-Fi controller. No more heating an empty cabin.
  2. Keep the door closed during heat-up. Peeking costs heat.
  3. Sauna together. A shared session costs exactly the same as a solo one, so the ritual gets cheaper per person.
  4. Enjoy the heat you like. If 70°C feels right, there's no need to run at 80°C.
  5. Look at your tariff. A fixed deal or a time-of-use tariff can beat the price cap, especially alongside solar or a battery.
  6. Look after the timber. Treating the exterior as soon as assembly is complete protects the walls that hold your heat, and maintains your investment for years to come. Our guide to Thermowood vs untreated spruce explains the options.

Ready to find the right sauna for your garden? Browse our barrel saunas or log cabin saunas, and if you're planning ahead for the colder months, our guide to why winter is the best time for a garden sauna is a good next read.

Frequently asked questions

How much electricity does an outdoor sauna use? A one-hour session with a 6kW heater uses around 7.5 kWh, including heat-up. A 3.6kW heater uses about 4.5 kWh and a 9kW heater about 11.25 kWh.

Is a garden sauna expensive to run? Less than many people expect. Two one-hour sessions a week with a 6kW heater cost roughly £17 a month at current rates.

How long does an outdoor sauna take to heat up? Typically 30 to 45 minutes with an electric heater. Allow up to an hour on cold winter evenings.

Is it cheaper to leave a sauna on all day? No. Holding a sauna at temperature for hours uses more energy than heating it when you need it. A timer gives you a hot sauna on arrival without the waste.

Do barrel saunas cost less to run? The curved shape means less air to heat than a square cabin of a similar size, which helps with heat-up. Wall thickness and glass area matter just as much, so compare those too.

Do I need a special electrical supply? Electric sauna heaters need a dedicated circuit, installed and connected by a qualified electrician. It's a routine job, and your electrician will confirm the right setup for your home. Our guide to planning permission for a garden sauna covers this alongside the other approvals worth knowing about.

Can I run a sauna on solar panels? Yes, particularly in summer. In winter, solar covers part of a session, and a battery charged on a cheap overnight tariff can make up the rest.

Will these costs change in 2027? Possibly. Ofgem sets the price cap every three months, with the January to March 2027 rate announced on 25 November 2026. We'll update this guide when it changes.

Sources

Running cost figures in this guide are estimates based on the stated assumptions and the Ofgem price cap at the time of writing. Your costs will depend on your tariff, usage and conditions. All electrical work, including heater installation, must be carried out by a qualified electrician.

Written by Peter Gibbs, founder of North Cabin.

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