Hot Tub Electricity Cost Calculator
Enter the heater's watts and the hours it runs each day to hold temperature, pick your state, and get the cost per day and month.
Hot tub cost
A08Scenario A
Sets the electricity rate. Pick US average if you're not sure.
From EIA for US average. Use the rate on your bill if you know it.
Rate used: 18.4¢/kWh · US average · EIA reference 2025–26 (data as of 2026-09-26) ·
240 V tubs usually have a 5.5 kW heater; 120 V plug-and-play tubs have smaller ones.
Typical hours to replace heat loss: warm climate about 0.8, mild 1.2, cold 1.8.
Estimated cost per month
Per year assumes the same use every day.
Estimate. Formula and sources are under “How it works”. Change any input; the result updates as you type.
Formula
How it works
- kWh per day = heater watts ÷ 1,000 × heater hours per day
- Cost per hour = heater watts ÷ 1,000 × rate
- Cost per month = kWh per day × days × rate
A 5.5 kW heater on a 240 V tub runs 1 to 2 hours a day just to replace the heat the water loses to the air. The colder the air, the bigger the loss, which is why the hours go from about 0.8 a day in warm climates to 1.8 in cold ones. A circulation pump adds another 100–300 W around the clock. Add it as a second line with the Appliance calculator; this page covers the heater. Typical total use is 150–300 kWh a month, more in winter or with a worn cover.
Sources: heater hours by climate (warm 0.8, mild 1.2, cold 1.8) from the Home Kilowatt spec, based on heat loss proportional to the air-to-water temperature gap. Electricity rate: EIA Electric Power Monthly table 5.6.A.
Worked example
A worked example
A 5,500 W heater running 1.5 hours a day uses 8.25 kWh a day. At the Texas rate of 15.5¢/kWh that's $0.85 per heater hour, $1.28 a day and $39.64 for a 31-day month.
Reference
Reference table
Hot tub heater cost per month at 18.4¢/kWh (US average)
| Warm · 0.8 h | Mild · 1.2 h | Cold · 1.8 h | |
|---|---|---|---|
| 5,500 W | $24.29 | $36.43 | $54.65 |
| 4,000 W | $17.66 | $26.50 | $39.74 |
| 1,500 W | $6.62 | $9.94 | $14.90 |
Questions
FAQ
Does a hot tub cost more in winter?
Yes. Heat loss grows with the gap between air and water temperature, so the heater runs longer. At the US average rate of 18.4¢/kWh, a 5,500 W heater costs an estimated $24.29 a month at 0.8 hours a day (warm climate) and $54.65 at 1.8 hours (cold climate).
Is a 120 V hot tub cheaper to run than a 240 V one?
Not necessarily. A smaller 120 V heater runs longer to replace the same heat loss. In California at 32.0¢/kWh, a 2,750 W heater for 3 hours uses the same 8.25 kWh as a 5,500 W heater for 1.5 hours, an estimated $79.20 a month either way. In cold weather, a small heater may not keep up at all.
Is it cheaper to leave a hot tub on or turn it off between uses?
This calculator estimates the cost of holding temperature. Reheating a full tub from cold takes a lot of energy at once, and we don't model that here. A good insulated cover lowers the holding cost in both cases.
How much does the circulation pump add?
100–300 W running 24 hours is 2.4 to 7.2 kWh a day. Add it with the Appliance calculator (watts and 24 hours) and send both lines to My bill.
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