How to size a sauna heater
How Harvia, HUUM and Finnleo match heater output to room volume, and why glass and log walls change the answer.
Guides
The decisions a sauna build or purchase involves, explained from makers' manuals and published guidance. Every fact links to its source.
All guides
Barrel vs cabin sauna
How barrel and cabin saunas differ in shape, weather and assembly, as their makers describe them.
Wood-burning vs electric sauna heater
What a wood-burning stove and an electric heater each need to install, and how long makers say they take to heat.
Sauna wood types
Which woods makers use for sauna walls and benches, and what they say about each.
Sauna ventilation
Where heater makers and the North American Sauna Society place a sauna's intake and exhaust vents.
Sauna stones
Which stones heater makers approve, what size to use, and how often to rearrange and replace them.
Traditional vs infrared sauna
How a traditional heated-rock sauna and an infrared room differ in heating method, temperature and use of water.
What is löyly?
What the Finnish word löyly means, and the temperatures and humidity sauna societies and makers describe.
Sauna bench layout
The bench heights, depths, widths and ceiling clearances heater makers and the North American Sauna Society give.
Sauna electrical supply and permits
What heater makers and the North American Sauna Society say about circuits, breakers, licensed electricians and permits.
Indoor vs outdoor sauna
What makers and the North American Sauna Society say changes between an indoor sauna and an outdoor one: weather, floor, glass, wiring and where it goes.
Sauna foundation and site
The bases makers accept for an outdoor sauna kit, how thick and how level, and what goes wrong on bare ground.
Sauna doors and glass
Which way a sauna door opens, standard door sizes and rough openings, glass versus wood, and what glass does to heater sizing.
Sauna insulation and vapor barrier
How much insulation makers call for in sauna walls and ceilings, and how the foil vapor barrier goes in.
Sauna controls and Wi-Fi
What sauna heater controllers do, how app control works, and the safety features makers build in: door sensors, timers and cut-offs.
How big should a sauna be?
Room sizes, bench length per person and ceiling heights from Finnleo, Thermory and the North American Sauna Society.
Sauna maintenance
How makers and the North American Sauna Society say to clean and look after a sauna: benches, floor, wood, stones and the heater.
Also see
Sauna heater size calculator
Enter your room to see the kW it needs, the heaters rated for it and the kits that fit