Sauna cost calculator

Two numbers matter: what it costs to get a sauna working in your home, and what each session costs after that. Change any figure below. Nothing is saved or sent anywhere; it all runs in your browser.

1. Upfront costs

Sauna price (£)

The sticker price, including the heater if it comes with one. Our guides list current prices.

Delivery (£)

Several retailers deliver free to mainland UK; others charge, especially for remote areas.

Assembly (£)

Retailer prices we found: Outdoor Living 365 £850 for a barrel; Steam & Oak £750; Polar Recovery £1,200–£2,000 for its Cube. Use £0 if you'll build it yourself.

Base (£)

A laid concrete base is about £60–£80 per m² (e.g. £800–£1,000 for 3 × 4m) on one 2026 cost guide; firms in other areas quote £90–£140 per m². £0 if you already have a level, strong patio.

Electrics (£)

One electrician's 2026 guide: £700–£1,100 for a supply to a detached building up to 15m away; £1,200–£2,000 for 15–30m with a sub-board. Plug-in infrared: often £0.

Other extras (£)

Wood treatment, stones, a bucket and ladle, a cover, a cold plunge… whatever isn't in the box.

2. Running costs

Heater type

Traditional electric Infrared

Switching type loads typical starting values. You can still edit them.

Heater power (kW)

On the product listing. Garden saunas commonly use 4.5–9kW heaters; plug-in infrared cabins we've listed run at 1.2–2.6kW.

Electricity price (pence per kWh)

Default is the Ofgem price cap average for Direct Debit, 1 October to 31 December 2026 (26.32p, no VAT on electricity this period). Use the unit rate on your bill if you know it.

Warm-up time (minutes)

Harvia's heater manual says a properly insulated sauna with the right size heater takes about an hour to reach bathing temperature. Cold weather and uninsulated walls can add time.

Session length, heater on (minutes)

Heater duty during session (%)

Our assumption, not a measured figure. Once hot, the thermostat switches the heater on and off. 50% means it's on half the time. Use 100% for a worst case.

Sessions per week

Your estimate

–All-in upfront cost

–Per session (– kWh)

–Per month

–Per year

–

Electricity only. Excludes the standing charge (you pay it anyway), maintenance, wood treatment and any change in energy prices. Estimates, not quotes.

How the calculation works

Energy per session (kWh) = heater kW × warm-up hours + heater kW × session hours × duty.

For the default 6kW heater: 6 × 1 hour + 6 × 0.75 hours × 50% = 8.25kWh. At 26.32p that's about £2.17 a session, or about £340 a year at three sessions a week.

The biggest unknowns are the warm-up time and the duty. A well-insulated, correctly sized sauna will do better than an uninsulated barrel in January. If you want a firm number for your own sauna, a plug-in energy monitor can't be used on a hard-wired heater, but your smart meter's in-home display will show the jump in usage when it's running.

Assumptions and sources

Electricity price: Ofgem, energy price cap unit rates, 1 October to 31 December 2026: 26.32p/kWh and 54.83p/day standing charge, Direct Debit, GB average.
Warm-up time: Harvia Cilindro PC70/PC90 installation and use manual, section 1.2.
Assembly prices: retailer product pages for Outdoor Living 365, Steam & Oak and Polar Recovery, checked 10 November 2026.
Base costs: JobPrices concrete base cost guide (prices checked October 2026) and Checkatrade shed base guide.
Electrics: M62 Electrical, garden office electrics cost 2026.
Heater duty: our assumption, as stated above.

Read the full breakdowns: garden sauna cost, all-in and sauna running costs.