Sauna electricity cost calculator
Enter what you know about your heater and how you use it. The answer updates as you type.
On the plate or the manual. Most home saunas are 4.5–8 kW.
Per kWh, from your bill. The US average is around $0.17.
Cold room to ready. Usually 30–50 minutes.
Only the part after it is up to temperature.
Count each heat-up, not each person.
A heater doesn't draw full power once the room is hot — it cycles. 35% is typical for an insulated room; raise it for a cold or glassy one.
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Fill in the fields to see your answer.
- Per session—
- Per month—
- Per year—
- kWh per year—
What this assumes
- Heat-up runs at full rated power. Close to true for an electric heater from cold — the thermostat isn't cutting in yet.
- Holding costs less than heating. The duty slider is the share of rated power drawn once the room is at temperature.
- Nothing is assumed about your room. Insulation, ceiling height and outside temperature all change the real duty — which is why that figure is yours to set.
- Months are 52.18 weeks ÷ 12, so weekly and annual figures stay consistent with each other.
How this calculation works
- Heat-up energy
- Hold energy
- Cost per session
- Per month and year
kWh = kW × (heat-up min ÷ 60) + kW × hold factor × (session min ÷ 60)
Heat-up runs at close to full rated power. Holding temperature does not — the thermostat cycles the element, so only a fraction of the rating is drawn. Multiply the total by your electricity price, then by sessions per week; annual is 52.18 weeks, and monthly is that divided by twelve.
| Heater | 35 min heat-up | + 45 min sit | Total |
|---|---|---|---|
| 4.5 kW | 2.6 kWh | 1.2 kWh | 3.8 kWh |
| 6 kW | 3.5 kWh | 1.6 kWh | 5.1 kWh |
| 8 kW | 4.7 kWh | 2.1 kWh | 6.8 kWh |
| 9 kW | 5.3 kWh | 2.4 kWh | 7.7 kWh |
Why the duty figure matters so much
Most sauna cost calculators multiply heater kilowatts by total time. That quietly assumes the heater draws its full rating from the moment you switch it on until you leave, which no thermostatically controlled heater does. Once the room reaches temperature the element cycles — on for a minute, off for two — and average draw falls to somewhere between a quarter and a half of the plate rating.
The practical consequence: a long sit in a hot room is much cheaper than a second heat-up from cold. If two people want a sauna on the same evening, going one after the other costs far less than heating twice.
Typical running costs
| Setup | Per session | Per month (3×/week) |
|---|---|---|
| 4.5 kW, 30 min heat-up, 45 min sit | ~$0.90 | ~$12 |
| 6 kW, 35 min heat-up, 45 min sit | ~$1.40 | ~$18 |
| 8 kW, 40 min heat-up, 60 min sit | ~$2.20 | ~$29 |
Want the longer version? What a home sauna really costs to run goes through why the usual estimate is too high, and how sauna heater sizing works covers picking the right heater in the first place.
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