Worked example
For a 1,600W sauna with 15 minutes of preheat and a 30-minute session: 1.6 kW × 0.75 hour = 1.2 kWh. At $0.17/kWh, the upper-bound session cost is about $0.20. Four sessions per week is roughly $3.54 per month and $42.43 per year.
Why the real number can differ
The heater may cycle after reaching its set point, lowering actual draw. A cold garage can increase warm-up time. Opening the door, cabin size, insulation, set temperature, and line voltage also matter. A plug-in energy meter can measure eligible 120V models, but only if its rating meets the sauna load and manufacturer instructions.
Use the site calculator
Enter the exact wattage and your own utility rate in the ownership calculator. Avoid generic national-average claims when your tariff is printed directly on your electric bill.
Sources and documentation
Specifications, claims, and installation requirements can change. Confirm the current manufacturer manual for the exact model and variant.