When planning a garden sauna, one of the most common questions is: What are the sauna running costs?
The answer depends on whether you choose an electric sauna heater or a wood-fired sauna stove – and on the typical energy consumption pattern of your sauna.
How Sauna Running Costs Are Calculated
A sauna does not consume energy evenly throughout the session. Instead, the cost of running a sauna comes from two phases:
Heating Up
The heater runs at full power until the air, walls, and stones reach the desired temperature.
Depending on sauna size, insulation, and outdoor temperature, this can take 30–90 minutes.
This is where most of the energy use and sauna operating costs occur.
Maintaining Heat (1 hour of sauna use)
Once hot, the energy demand drops significantly.
Electric sauna heaters cycle on and off via thermostat; wood stoves only need small refills.
Running costs during this phase are much lower.
Key point: Most sauna running costs come from heating up, not from the actual sauna session.
Electric Sauna Heater Running Costs
Energy curve & calculation
Heating up: A 6 kW electric sauna heater runs for 45 minutes at full power → 0.75 h × 6 kW = 4.5 kWh.
Maintaining (1 hour of use): The heater cycles at approx. 50 % load → 1 h × 3 kW = 3.0 kWh.
Total = 7.5 kWh.
Estimated sauna running costs (electricity at €0.40/kWh, incl. heating up + 1 hour of use):
6 m³ sauna, 6 kW electric heater → 7.5 kWh → €3.00
10 m³ sauna, 9 kW electric heater → ~13.5 kWh → €5.40
14 m³ sauna, 12 kW electric heater → ~21 kWh → €8.40
Pros
Maximum comfort: switch on and enjoy.
Precise temperature control.
No wood storage or cleaning required.
Cons
Dependent on electricity prices.
Higher sauna operating costs compared to wood.
Wood Sauna Stove Running Costs
Energy curve & calculation
Heating up: A 12 kW wood sauna stove requires about 5–7 kg of wood.
Maintaining (1 hour of use): Another 3–4 kg of wood is needed.
Total = 8–11 kg of wood.
Estimated sauna running costs (wood at €120/m³ ≈ €0.24/kg, incl. heating up + 1 hour of use):
6 m³ sauna, 8 kW wood stove → 6–8 kg wood → €1.50–2.00
10 m³ sauna, 12 kW wood stove → 8–11 kg wood → €2.00–2.60
14 m³ sauna, 18 kW wood stove → 11–14 kg wood → €2.60–3.40
Pros
Lower sauna operating costs.
Independent of the electricity grid.
Traditional sauna experience with real fire.
Cons
More effort: wood refilling, storage, ash removal.
Less precise temperature control.
Sauna Running Costs at a Glance (Heating Up + 1 Hour of Use)
| Sauna Size | Electric Heater (at €0.40/kWh) | Wood Stove (at €0.24/kg) |
|---|---|---|
| 6 m³ | ~€3.00 | ~€1.50–2.00 |
| 10 m³ | ~€5.40 | ~€2.00–2.60 |
| 14 m³ | ~€8.40 | ~€2.60–3.40 |
In Ireland, wood sauna stoves often cost only half as much to run compared to electric sauna heaters.
Important Note on Sauna Running Costs
These numbers are estimates based on typical heater performance, average energy prices, and one hour of sauna use.
Actual sauna running costs may vary depending on:
local energy prices (electricity vs. firewood)
sauna size and insulation
outdoor temperature and season
individual heating habits
This guide gives you a realistic orientation, not an exact calculation.
Conclusion: Which Sauna Heater Is Cheaper to Run?
Electric sauna heaters: higher running costs but maximum comfort and precise control.
Wood sauna stoves: lower operating costs, more effort, authentic sauna feeling.
For details on how to correctly size your sauna heater, check our dedicated guide here.
