Hot tubs bring the relaxing comfort of a commercial spa into your home without the spa price tag. An entire months' use of your own hot tub doesn't even amount to the price of spending a few hours at a typical spa. Despite this, your hot tub uses more wattage than any other appliance in your home.
Determining the voltage of your hot tub's water heater is important to estimating how much electricity your hot tub uses. According to the Otter Tail Power Company, a 120-volt water heater uses 1,500 watts (W). A 240-volt heater uses 6,000 W.
Circulation pumps use the same amount of energy as a 120-volt water heater. When calculating your hot tub's electricity use, use 1,500 W as an estimate.
At the time of publication, electricity costs more than 11 cents per kilowatt-hour. Using this figure, you can calculate how much it costs to use your hot tub. Divide your hot tub's wattage by 1,000 to convert it to kilowatts. For instance, a hot tub with a 240-volt heater uses about 7,500 W, or 7.5 kW. Estimate how many hours per month you use the hot tub and multiply that number by the number of kilowatts the hot tub uses. For example, 30 hours a month multiplied by 7.5 kW is 225 kilowatt-hours per month. At 11 cents per kilowatt-hour, the hot tub costs about $25 in electricity per month and $300 per year.
When buying a new hot tub, choose one that will consume as little electricity as possible. The Seattle City Light conservation agency advises you to choose a hot tub insulted with at least 6 inches of dense foam material. Also choose a model that uses one motor for heating and a separate motor for jet streams.