The NumbersJuly 20267 min read
What does a sauna actually cost to run? The real per-session math
Heater kilowatts × your electricity rate × how long you sit. Work out the true per-session and monthly cost of any sauna — and why it's cheaper than almost everyone guesses.
"I'd love a sauna, but the electric bill…" is the most common objection we hear, and it's almost always based on a guess that's several times too high. The math is simple once you have three numbers, so let's do it properly — for electric hot-rock saunas, infrared cabins, and wood-fired stoves — and see what a real month of near-daily use costs. Or skip ahead and plug your own numbers into the calculator below.
Try it with your numbers
Your sauna, your electricity rate
Per session
38¢
Per month
$8.34
Per year
$100
Assumes the heater averages 60% of rated draw across a session (full power heating up, cycling to hold temperature). Preheat you're not present for is included in that factor. Estimates only — your insulation, climate, and habits move the number.
The formula
Running cost per session = heater power (kW) × session hours × your electricity rate ($/kWh) × a duty-cycle factor. The duty-cycle factor matters: a heater draws full power heating up, then cycles on and off to hold temperature, so it averages roughly 50–65% of its rated draw over a session. We'll use 0.6 as a reasonable middle estimate.
A worked example: electric hot-rock sauna
Take an 8 kW heater, a 30-minute session (0.5 h including a bit of preheat you're present for), and the US average residential rate of about 16–17 cents per kWh. That's 8 × 0.5 × 0.16 × 0.6 ≈ $0.38 per session. Sauna five times a week and you're at roughly $8 a month. Even in a high-rate state at 30 cents/kWh, you're under $15 a month for near-daily use.
Infrared runs cheaper still
Infrared cabins draw less — often 1.6–2.8 kW — and while sessions run longer (45 min), the lower power wins. A 2 kW cabin for 45 minutes: 2 × 0.75 × 0.16 × 0.7 ≈ $0.17 per session. The higher duty-cycle factor reflects that infrared panels spend more time at full draw, but the absolute cost is still tiny — a few dollars a month.
Wood-fired: no electric bill, different math
A wood stove's 'fuel' is firewood. A single session burns roughly 10–15 lbs of wood; at typical seasoned-hardwood prices that's often $1–$3 a session, more than electric but with zero grid dependency and no electrician bill up front. Factor in the one-time chimney cost when you compare.
The costs that dwarf the electricity
The running cost is rarely the real number to worry about. For an electric sauna the dedicated 240V circuit (often $600–$2,500 installed) usually costs more over the sauna's life than years of electricity. Size the heater right, insulate the room, and the per-session energy cost stays in loose-change territory.
Common questions
- How much does it cost to run a sauna per month?
- For near-daily use (5 sessions/week), most home saunas land between $8 and $20 a month in electricity at typical US rates — electric hot-rock heaters around $8–15, infrared often under $10. Wood-fired trades the electric bill for firewood at roughly $1–3 per session.
- Does preheating cost a lot?
- Preheating is when the heater draws full power, but it's brief — 30–45 minutes for a traditional room, less for infrared. It's already baked into the duty-cycle factor in our formula. Using a Wi-Fi controller to preheat only when you'll actually use the sauna avoids waste.
- What's the biggest hidden cost?
- For electric saunas, the dedicated 240V circuit — a real electrical job that can run $600–$2,500 depending on the panel and the run. It's a one-time cost, but it usually exceeds years of the electricity itself, so budget for it before you buy the heater.
Sources
- Electric Power Monthly: Average Price of Electricity to Ultimate Customers · U.S. Energy Information Administration (2025)
- NFPA 70: National Electrical Code (NEC) · National Fire Protection Association (2023)
- Association Between Sauna Bathing and Fatal Cardiovascular and All-Cause Mortality Events · JAMA Internal Medicine (2015)