How to choose a sauna heater

1. Size it to the room

Heaters are rated by the room volume they heat, in cubic feet. Multiply length by width by height. A 6 × 7 ft room with a 7 ft ceiling is 294 cubic feet.

Glass and stone pull heat out of the room, so count them as extra volume. Heater maker Harvia’s rule is that each square meter of glass or stone adds the load of 1.2 cubic meters, about 3.9 cubic feet per square foot. For bare, uninsulated log walls it raises the factor to 1.5 for the whole room. A glass door of about 17 square feet adds roughly 67 cubic feet.

Then pick a heater whose rated range covers your number. Near the top of a range, the next size up heats faster. The sizing calculator does the math and shows every heater that fits.

2. Electric or wood-burning

• Electric heaters run from a wall control or an app, can preheat on a schedule, and suit indoor rooms and homes with spare electrical capacity.
• Wood-burning stoves need no electrical service. They need a chimney, the clearances in the stove’s manual, and someone to tend the fire. They suit outdoor, cabin and off-grid saunas. Thru-wall models load from outside the hot room.

3. Plan the electrical service

Electric sauna heaters run on 240 V and draw serious current, so they need a dedicated circuit and a disconnect within sight of the heater. The NEC covers sauna heaters under Article 424. GFCI rules vary: some heater makers recommend against a GFCI breaker while some jurisdictions require one outdoors, so your electrician and inspector decide. HUUM’s published draws at 240 V, single phase:

A licensed electrician sizes the wire and breaker from the heater’s manual. Check your panel has room before you order a 12 kW or larger heater. Full electrical requirements.

4. Match the control and the stones

Most electric heaters ship without a control. HUUM heaters run on a UKU control, and models from 12 kW up also need the UKU extension box. Every heater lists the stone weight it needs. A HIVE 12 holds 528 lb of stones, while a DROP holds 122 lb, so order the stones with the heater to avoid a second freight charge.

5. Plan the delivery

Heaters and stones ship by freight on a pallet, delivered curbside. How freight works. Ask for the delivered price with your ZIP code before you buy.

Questions people ask

What size sauna heater do I need?

Find the room’s volume in cubic feet, add about 3.9 cubic feet for every square foot of glass or stone, and multiply by 1.5 if the walls are bare logs. Choose a heater whose rated range includes that number.

Does an electric sauna heater need its own circuit?

Yes. Sauna heaters run on a dedicated 240 V circuit with a disconnect within sight of the heater. A licensed electrician sizes the wire and breaker from the heater’s amp draw and local code.

Electric or wood-burning?

Electric heaters run from a wall control, warm up on a schedule and suit indoor rooms. Wood-burning stoves need no electrical service but need a chimney, clearances and someone to tend the fire, so they suit outdoor and off-grid saunas.

Size your heater Shop heaters

Sources: Harvia, selecting heater power; Peak Saunas, NEC sauna requirements; HUUM 2025 product specifications. Electrical rules vary by jurisdiction; follow your electrician and local inspector.