Design & Build Tools

What size sauna heater do I need?

Enter your room and we'll size the heater. An undersized heater never reaches temperature and burns out early; an oversized one runs cooler and lasts longer — so when the answer lands between two models, we always send you up.

1 Room size

Length ft Width ft Height ft

A typical 2-person home sauna is 200–350 cu ft.

2 Glass & cold surfaces

Glass doors and windows, tile, concrete or stone — anything that isn't insulated wood. Leave at zero if your room is all timber.

Width ft Height ft

3 Where it's built

Indoor, insulatedFramed and insulated room inside a building Outdoor or uninsulatedBarrel sauna, cabin, shed or garage conversion

Heaters that fit

All heaters →

How sauna heater sizing works

Volume, not floor area

Heaters warm air, so the ceiling matters as much as the footprint. A 6×5 room with a 7 ft ceiling is 210 cu ft and needs roughly 4.7 kW; raise the ceiling a foot and you've added another 30 cu ft to heat.

Glass is a heat leak

A glass door behaves like a much larger volume of air. We count every square foot of glass, tile or stone as 7 extra cubic feet — a standard 2×6 ft door alone adds 84 cu ft to the load.

Outdoors costs 50%

Barrel saunas, cabins and garage conversions lose heat through walls, floor and roof year-round. Uninsulated builds carry a 50% uplift so the room still reaches temperature in winter.

Always round up

Never size down to save a few hundred dollars. An undersized heater runs flat out, never quite gets there, and fails early. A slightly larger one reaches temperature sooner and cycles gently.