How Much Does a Garden Sauna Cost to Run in the UK? Real Numbers for 2026
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One of the first questions people ask before buying a garden sauna is: how much will it actually cost to run? The answer depends on three things — your heater type, how often you use it, and your electricity tariff. Here are the real numbers for 2026.
Electric Sauna Running Costs
Most of our outdoor saunas use a Harvia Cilindro PC90 (9kW) electric heater. At the current UK average electricity rate of roughly 24.5p per kWh (Ofgem cap, Q2 2026), a typical 60-minute session costs between £1.47 and £2.20 depending on how long the heater cycles on and off once the sauna reaches temperature.
Here’s the maths:
- Heat-up phase: 30–40 minutes at full power = 9kW × 0.6 hours = 5.4 kWh = £1.32
- Maintenance phase: The heater cycles at roughly 40–50% duty once at temperature = ~4kW × 0.5 hours = 2 kWh = £0.49
- Total per session: approximately 6–8 kWh = £1.47–£1.96
If you sauna three times a week — which is the most common pattern among our customers — your annual electricity cost is roughly £230–£305 per year. That’s less than a Netflix and Spotify subscription combined. For a precise figure based on your own heater size and tariff, try our Sauna Running Cost Calculator.
Electric Sauna with Wi-Fi Remote
Several of our saunas offer the Harvia Wi-Fi module, which lets you preheat from your phone. The running cost per session is identical — the module itself draws negligible power. The real benefit is convenience: start heating while you’re driving home, and it’s ready when you walk through the door. Available on our Sanctuary sauna (from £15,395) and M-Sanctuary (from £11,899).
Wood-Burning Sauna Running Costs
A wood-burning heater like the Harvia 20 Pro uses no electricity at all — just firewood. A typical session requires 8–12kg of kiln-dried hardwood. At current UK prices of roughly £5–£7 per bag (roughly 10kg), each session costs £5–£8 in fuel.
That’s more expensive per session than electric, but wood-burning saunas don’t need a 32A electrical supply — which saves you the £400–£800 electrician cost for installation. If you’re off-grid or on a rural site without mains power, wood-burning is your only practical option.
Annual cost comparison
| Heater Type | Cost Per Session | 3x/Week Annual Cost | Installation Electrical Cost |
|---|---|---|---|
| Electric (Harvia Cilindro 9kW) | £1.50–£2.00 | £230–£310 | £400–£800 (32A supply) |
| Wood-burning (Harvia 20 Pro) | £5–£8 | £780–£1,250 | £0 |
| Infrared (carbon panel, 2.4kW) | £0.35–£0.60 | £55–£95 | Standard 13A plug |
Infrared Sauna Running Costs
Indoor infrared saunas (from £2,395) run on far less power — typically 1.5–2.4kW. A 40-minute session costs just 35–60p. They also plug into a standard 13A socket, so there’s no electrician needed. The trade-off: infrared heats your body directly rather than the air, so the experience is gentler and less intense than a traditional Finnish sauna.
What About the Sauna Itself?
Running costs are only half the picture. Here’s what our outdoor saunas cost to buy:
- Heat Quad 5-Person — from £9,990 (electric) / £10,400 (wood-burning)
- M-Sanctuary 4-6 Person — from £11,499
- The Sanctuary — from £14,995
- Fort Soleil 5-Person — from £14,499
- The Hideout 6-Person — from £19,995
All prices include the heater, stones, benches, interior lighting, and UK delivery. Browse our full outdoor sauna range.
Tips to Reduce Running Costs
- Insulation matters most. All our saunas use mineral wool insulation and double-wall construction. Cheaper saunas with single-wall timber lose heat 2–3x faster and cost significantly more to run.
- Don’t oversize. A 2-person sauna heats up in 20 minutes; an 8-person sauna takes 40+. Buy for how you’ll actually use it.
- Use a timer or Wi-Fi control. Heating only when needed — not leaving it on for hours — is the single biggest cost saver.
- Economy tariffs. If you sauna in the evening, check whether your energy supplier offers a cheaper off-peak rate.
Frequently Asked Questions
How much does it cost to run a sauna per session in the UK?
An electric sauna with a 9kW heater costs approximately £1.50–£2.00 per 60-minute session at 2026 UK electricity rates. Wood-burning saunas cost £5–£8 per session in firewood. Infrared saunas are the cheapest at 35–60p per session.
How much electricity does an outdoor sauna use?
A typical session uses 6–8 kWh for a 9kW electric heater. At 24.5p/kWh, that’s under £2. Over a year with three sessions per week, expect £230–£310 in electricity costs.
Is a wood-burning sauna cheaper to run than electric?
No — wood-burning saunas cost more per session (£5–£8 vs £1.50–£2.00). However, they require no electrical installation, which saves £400–£800 upfront. They’re the only option for off-grid locations.
Do you need a special electrical supply for a garden sauna?
Electric saunas with heaters above 6kW need a dedicated 32A supply installed by a qualified electrician. This typically costs £400–£800 depending on the distance from your consumer unit. Infrared saunas use a standard 13A plug.
What is the cheapest type of sauna to run?
Infrared saunas are the cheapest to run at 35–60p per session. They use 1.5–2.4kW compared to 9kW for a traditional Finnish sauna. However, the experience is different — infrared heats your body directly rather than the air.
Need help choosing? Call our team on 0330 133 6617 — we’ll walk you through the options and give you a quote within 24 hours.