Free tool
Sauna Heater Size & Running Cost Calculator
How many kW does your sauna heater need, and what will it cost to run? Pick one of our outdoor saunas to see the manufacturer's recommended heater size, or enter the inside dimensions of any sauna. The calculator then estimates the electricity cost per session and per month at your own electricity rate.
How the calculator works
- Our saunas: the heater size is the recommendation published by the manufacturer, Dundalk LeisureCraft, for that model and interior volume.
- Custom size: a common rule of thumb is about 1 kW of heater power per 50 cubic feet of interior space. Solid-wood walls without insulation (like most barrel saunas) and large glass areas lose more heat, so the calculator adds 10–20% for each before rounding up to a standard heater size.
- Running cost: the heater runs at full power while the sauna preheats. After that, the thermostat switches it on and off, so we count roughly half its power for the time you spend inside. Cost = heater kW × hours × your price per kWh.
Frequently asked questions
Is a bigger heater better?
Not necessarily. An undersized heater never reaches a comfortable temperature, but an oversized one heats the air too fast and cycles on and off often. Follow the heater manufacturer's minimum and maximum room volume for each model.
What electrical supply does an outdoor sauna heater need?
Most residential electric sauna heaters of 4.5–10.5 kW run on a dedicated 240 V circuit. The breaker size and wire gauge depend on the heater model, so always follow the heater's installation manual and have a licensed electrician do the hookup.
Can I use a wood-burning stove instead?
Yes for most barrel and pod saunas, including the Harmony, Serenity, Tranquility, Elation and MiniPOD. The Luna is electric only. A wood stove needs no electrical hookup but does need a chimney and firewood.
Want to go deeper? Read our guide to sizing a sauna heater (6 kW vs. 8 kW), compare indoor vs. outdoor sauna costs, or browse our sauna heaters and 4-person outdoor saunas.
Your result
– kW
- Interior volume
- –
- Current draw at 240 V
- –
- Power cost per session
- –
- Power cost per month
- –
Estimates only. The heater runs at full power while preheating, then the thermostat cycles it on roughly half the time. Wind, outside temperature and how often the door opens change the real numbers. Your heater's installation manual and a licensed electrician decide the final wiring.