Picking a sauna heater is mostly one sum and two choices. Work out your sauna's size, decide between electric and wood, then match a heater to the room. Here's the quick version, and the detail behind it.
The quick version
- Measure the inside of your sauna (interior length × width × height, plus a little extra for glass).
- Choose your fuel: electric for convenience, wood for the crackle and the ritual.
- Match the kW to your room, then check the electrics (or the chimney) before you order.
Not sure? Send us your sauna's dimensions at hello@phoebe-wellness.com and we'll do the math with you.
Step 1: Work out your sauna's size
Measure the inside of the sauna, the room you sit in, not the outside of the cabin. Multiply interior length × width × height in feet to get cubic feet. A 6 × 7 × 7 ft interior is 294 cubic feet.
Glass, tile, brick and stone soak up heat, so they count as extra room volume. Add 2 cubic feet for every square foot of glass, tile, brick or stone, including a glass door.
Example: that same 294 cubic foot sauna with 20 square feet of glass comes to 334 cubic feet.
Then use this rule of thumb: roughly 1 kW for every 45 cubic feet. That puts the example at about 7.5 kW, so you'd look for a heater at or just above that size. If your sauna is outdoors, in a cold climate or poorly insulated, add about 25% to the kW. Finally, check the heater's own recommended room size. If you land between two sizes, go up.
On our sauna pages, the Recommended Heater Size already allows for the glass in that model.
Try it: heater size calculator
Enter your sauna's interior size above and we'll work out a starting point.
A guide, not a guarantee. Glass areas are typical estimates, and barrel volumes allow for the round shape. Always check the heater's own recommended room size, and ask your electrician to confirm the circuit.
Step 2: Electric or wood?
Electric heaters
Flip a switch, set a temperature, and the sauna is ready when you are. Most come with a control included, and many can be scheduled so the sauna is warm when you get home. Best for indoor saunas and anyone who wants simple.
Wood-burning stoves
A real fire, no electrical supply needed, and a ritual of its own. Stoves need a chimney and proper clearances to the walls and ceiling, so plan the install before you buy. Best for outdoor and off-grid saunas, and for fire lovers.
Step 3: Choose a brand and series
| Brand | What we carry |
|---|---|
| Harvia | The widest range. Electric heaters from compact (Vega) to large (Virta Pro, Club), wall-mounted (The Wall), combi heaters with a built-in steamer (Virta Combi), and wood stoves from Cilindro to Legend, Linear and Pro, including stoves loaded from outside the sauna. |
| Huum | Electric heaters in the Drop, Cliff, Steel, Core and Hive families, with mini versions for smaller rooms, all with the UKU control. Wood stoves in the Hive Wood and Hive Flow families. |
| Saunum | Air heaters with a built-in air equalizer and the AirIQ WiFi control, in the Air, Air Perfect and Air L series. We also carry the AirSolo equalizer on its own. |
| Narvi | Wood-burning stoves, including the Kuru, Kaamos, NC and Luosto series, and a model with a water tank. |
Controls
The control is what you'll touch every day, so it's worth a thought. Electric heaters come with one of three kinds.
- Built-in: a simple control panel on the heater itself. Nothing extra to mount or connect.
- Local: a separate control unit that you use at the sauna. No WiFi or app needed.
- WiFi: a connected control you can use from your phone, so you can set the temperature and schedule the sauna to be warm when you get home.
The product page for each heater shows which control is included.
Packages or heater only?
Most of our heaters are sold as packages with the right stones and a control. Some wood stoves are available as heater only, and the stones, chimney kit and extras are offered as add-ons on the product page.
Before you order: the electrics
Home saunas usually run on a dedicated 240V single-phase circuit. Here's the quick math: kW × 1000 ÷ 240 = amps, and electricians usually size the breaker about 25% above that.
As a guide, Huum's own sizing sheet lists a 4.5 kW heater on a 30 amp breaker, a 7.5 kW on 40 amps and a 9 kW on 50 amps. Treat those as guidelines only. Your electrician makes the final call, so book them early.
Before you order: wood stoves
- Check the manual for the minimum clearances to walls and ceiling.
- Plan a floor protector and a chimney that suits your sauna (we offer chimney kits as add-ons).
- Check your local fire and building rules.
Quick questions
My sauna is between two heater sizes. Which one?
Go up. A slightly larger heater copes better with glass, cold weather and a door that gets opened a lot.
Do I need a bigger heater for an outdoor sauna?
Outdoor saunas lose heat faster, especially in colder climates, so add about 25% to the kW and size up if you're between heaters.
Can you help me choose?
Always. Tell us your sauna's size and what you're building and we'll do the math.
Your reset is waiting.