About the Hot Tub Cost Calculator
This calculator estimates what it costs to run a hot tub using the standard appliance energy-cost formula: watts × hours ÷ 1000 to get kilowatt-hours, then kilowatt-hours × your electricity rate to get a dollar cost. A hot tub has two main electrical loads — the heater, which keeps the water at your set temperature, and the circulation pump, which drives filtration and jets — so the tool totals the energy used by both.
The formula
For each load, daily energy in kilowatt-hours is watts × hours per day ÷ 1000. Adding the heater's and pump's daily kWh gives total daily energy use. Multiplying that by your electricity rate ($/kWh) gives the daily operating cost. The monthly figure multiplies the daily cost by 30, and the annual figure multiplies it by however many days per year you actually run the tub (365 for year-round use, fewer if you drain it seasonally).
Getting accurate results
- Check your hot tub's spec plate or owner's manual for the actual heater and pump wattage — these vary widely by model, from roughly 1,500 W heaters on small 120V plug-in spas to 5,500 W or more on large 240V units.
- The heater "hours per day" input is an equivalent run time, not a literal duty cycle — heaters cycle on and off to hold temperature, so use your utility bill or manufacturer estimate to calibrate this figure rather than guessing.
- Pull your electricity rate directly from a recent utility bill, including delivery and supply charges, since rates vary by region and season and a national average can be off by a wide margin.
Using the result
The annual cost is a starting point for budgeting, not a guarantee — actual costs shift with ambient temperature, wind exposure, cover condition, water temperature setting, and how often the tub is used. Compare your result against a recent electricity bill before and after hot tub use to sanity-check the estimate, and revisit the run-hours inputs if your climate or insulation is unusual.