Enter your cabin’s internal size to get the recommended heater output in kilowatts, for both traditional and infrared saunas.
0 kW
How this works
First it works out the cabin volume: length × width × height in metres. For a traditional sauna the long-standing rule of thumb is roughly 1 kW of heater per cubic metre of well-insulated cabin, so a 6 m³ room needs about a 6 kW heater. The result is nudged towards the heater sizes actually sold.
Infrared cabins heat your body directly rather than the air, so they need far less power for the same space. This uses roughly 0.5 kW per cubic metre as a planning figure for the total panel output.
Ticking the margin box adds extra output to cover heat lost through a glass door, a poorly insulated wall or an outdoor location, where the standard rule under-sizes the heater.
Assumptions: this is a sizing guide, not a substitute for the manufacturer’s chart. Always check the heater’s own rated room volume and follow the wiring and clearance instructions. A 6 kW or larger heater usually needs a dedicated circuit and a qualified electrician.