Sauna Running Cost Calculator
What does it actually cost to use your sauna? Adjust dimensions, heater type and electricity price — and get heat-up time, kWh per session, and monthly cost instantly.
Sauna & usage
How the cost is calculated
For electric heaters we compute the energy to heat the air (volume × ΔT × ρ × c) plus a thermal-mass factor (~3×) for walls, benches, and stones. We divide by the heater's efficiency and add the maintenance load during the session. For wood-fired we use an empirical model based on ~15 kg of birch per session.
How long does it take to heat a sauna?
35–60 minutes for a correctly sized electric heater to reach 80 °C. An undersized heater never reaches temperature, an oversized one wastes energy. Wood-fired saunas take 30–60 min depending on size and chimney draw.
Is wood-fired or electric cheaper to run?
In the calculator's starting room, 2.5 × 2.5 m with a 9 kW heater, an electric session uses about 10.7 kWh, which costs €3.2 at €0.30 per kWh. A wood-fired session burns about 15 kg of birch, roughly €4.0. Electric is the cheaper of the two below about €0.37 per kWh, and wood is cheaper above it. Enter your own room and electricity price above to see where you land. Wood also means handling fuel and having the chimney swept.
How much does good insulation save?
An uninsulated outdoor log-cabin uses about 30 % more energy than an insulated build. Glass doors and windows further increase losses — each m² of glass adds about 1.2 m³ of effective volume.