SaunaCosts

Sauna breaker and wire size

A sauna heater is a continuous load, so its breaker and wire are sized at 125 percent of its draw. On 240 V a 6 kW heater draws 25.0 A and needs a 35 A breaker with 8 AWG copper wire, and a 3 kW heater needs a 20 A breaker with 12 AWG copper. A household 120 V circuit tops out at 20 A, about 1.9 kW of heater.

Breaker and wire by heater size

At 240 V, often called 220 V
HeaterBreakerCopper wire
1.8 kWdraws 7.5 A15 A14 AWG
2.4 kWdraws 10.0 A15 A14 AWG
2.6 kWdraws 10.8 A15 A14 AWG
3 kWdraws 12.5 A20 A12 AWG
4.5 kWdraws 18.8 A25 A10 AWG
6 kWdraws 25.0 A35 A8 AWG
7.5 kWdraws 31.3 A40 A8 AWG
8 kWdraws 33.3 A45 A6 AWG
9 kWdraws 37.5 A50 A6 AWG

A household 120 volt circuit tops out at 20 amps, about 1.9 kW. Above that the heater either runs on 208 or 240 volts, or it is a listed appliance whose own marked rating governs. See the NEC 422 note below.

At 120 V, often called 110 V
HeaterBreakerCopper wire
1.8 kWdraws 15.0 A20 A12 AWG
2.4 kWdraws 20.0 Aover 20 Anot a 120 V circuit
2.6 kWdraws 21.7 Aover 20 Anot a 120 V circuit
3 kWdraws 25.0 Aover 20 Anot a 120 V circuit
4.5 kWdraws 37.5 Aover 20 Anot a 120 V circuit
6 kWdraws 50.0 Aover 20 Anot a 120 V circuit
7.5 kWdraws 62.5 Aover 20 Anot a 120 V circuit
8 kWdraws 66.7 Aover 20 Anot a 120 V circuit
9 kWdraws 75.0 Aover 20 Anot a 120 V circuit
At 208 V
HeaterBreakerCopper wire
1.8 kWdraws 8.7 A15 A14 AWG
2.4 kWdraws 11.5 A15 A14 AWG
2.6 kWdraws 12.5 A20 A12 AWG
3 kWdraws 14.4 A20 A12 AWG
4.5 kWdraws 21.6 A30 A10 AWG
6 kWdraws 28.8 A40 A8 AWG
7.5 kWdraws 36.1 A50 A6 AWG
8 kWdraws 38.5 A50 A6 AWG
9 kWdraws 43.3 A60 A4 AWG

For any other heater power, the sauna electrical requirements calculator works it out at 240, 208 or 120 volts.

When the manufacturer publishes a smaller circuit

Sauna makers routinely specify one standard size below what this page computes: 40 amps for an 8 kW heater, 30 for a 6 kW. That is not necessarily an error. NEC 422 covers appliances, and where a listed appliance is marked with its own branch circuit rating, that marked rating is what the installer follows: the maker tested the assembly and had it listed.

Wire sizes are the 60 degree C copper column of NEC 310.16, the column that governs terminations on ordinary residential breakers, with the NEC 240.4(D) small conductor rule applied on top: 14 AWG is capped at 15 amps and 12 AWG at 20 regardless of what the ampacity table alone would allow.

This is a planning figure. Circuit length, ambient temperature, conduit fill, aluminum conductors and your local amendments all change the answer, and the install has to be signed off by a licensed electrician who has seen the actual run.

Breaker and wire questions

How many amps does a 2,600 watt sauna heater draw on 220 or 240 volts?
A 2.6 kW heater draws 11.8 A at 220 V and 10.8 A at 240 V: watts divided by volts. A sauna heater is a continuous load, so the circuit is sized at 125 percent of that draw, which puts it on a 15 A breaker with 14 AWG copper wire at either voltage.
Do these figures apply to a 230 volt supply outside the US?
No. Every figure on this page follows the US National Electrical Code and US wire gauges. Where the supply is 230 V, as in Europe and much of Africa and Asia, local wiring rules and metric cable sizes apply, so ask a local licensed electrician.
Is a 30 amp 220 V breaker enough for a sauna heater?
On 240 V, the supply often called 220 V, a 30 A breaker covers a heater up to 5.7 kW, with 10 AWG copper; on 208 V it covers up to 4.9 kW. A 6 kW heater draws 25.0 A at 240 V, and 125 percent of that is 31.3 A, so the general rule puts it on a 35 A breaker with 8 AWG copper. Of the 72 saunas in our catalog with a 6 kW heater, 43 publish a 30 A circuit instead. That is not necessarily an error: where a listed appliance is marked with its own branch circuit rating, that marked rating is what the installer follows.
Is a 40 amp breaker with 10/2 wire right for a 3 kW sauna heater on 110 V?
No. On a 120 V circuit, the supply often called 110 V, a 3 kW heater draws 25.0 A, and the continuous load rule asks for 31.3 A. A household 120 V circuit tops out at 20 A, about 1.9 kW of heater, so 3 kW is not a 120 V circuit, and a 40 A breaker does not make it one. The wire is wrong too: 10/2 cable is 10 AWG copper, which carries 30 A in the 60 degree C column, less than a 40 A breaker. On 240 V the same heater draws 12.5 A and needs a 20 A breaker with 12 AWG copper.
What size breaker and wire does a 3 kW sauna heater need?
On 240 V it draws 12.5 A and needs a 20 A breaker with 12 AWG copper. On 208 V it draws 14.4 A and needs a 20 A breaker with 12 AWG copper. On a 120 V circuit, often called 110 V, it draws 25.0 A, past the 20 A ceiling of a household circuit, so it is not a 120 V circuit.

Which saunas use each heater size

259 of the 417 saunas in our catalog publish a heater power. Each size links up to 3 of them and the calculator set to that size.

44 more heater sizes, each on fewer than 5 saunas

Heater size for any room

Prices and specifications verified September 27, 2026, and re-checked weekly after that. How these numbers are checked.

Browse the models by category

Each category page lists every model in it, with its verified price and specifications, in one table:

More guides

Free guide: sizing and budgeting a home sauna

A fill-in worksheet covering room sizing math, the electrical checklist, indoor vs outdoor decisions, a full cost worksheet, and ten questions to ask the dealer.