How Much Electricity Does a Water Heater Use?
How much electricity does a water heater use? Elements are rated 4,500 to 5,500 watts. Enter your wattage and rate below for the exact cost.
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Water heater electricity cost calculator
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How the math works: 4,500 W × 3 hours ÷ 1,000 = 13.5 kWh a day. × 30 days = 405 kWh a month. × $0.165 per kWh (the 2024 U.S. average) = about $66.83 a month.
A standard 40-gallon electric resistance water heater has heating elements rated at 4,500 to 5,500 watts, though only one element runs at a time in normal operation. Because it's one of the highest-wattage appliances in a home and runs whenever hot water is used up, it's typically one of the larger contributors to an electric bill.
What affects how much electricity a water heater uses
- Tank size: a larger tank holds more water to heat and reheat.
- Heating elements: most tanks have two, but only one runs at a time, cycling on when the water cools below the set point.
- Hot water use and thermostat setting: both set how often and how long the elements run.
- Tankless models: these heat water only as it flows, but typically need a much higher wattage while running.
How to reduce your water heater's electricity use
- Lower the thermostat to 120°F, which is hot enough for most households and reduces standby heat loss
- Insulate the tank and the first few feet of hot water pipe if the tank feels warm to the touch
- Fix dripping hot water faucets promptly, since every drip is water the heater has to reheat
- Spread out high hot-water-use activities (showers, laundry, dishwasher) rather than running them back-to-back
Typical wattage figure: 4,500-5,500 W (40-gallon electric resistance tank). Source: DOE-developed appliance energy table, reproduced by Virginia Cooperative Extension (Virginia Tech), publication BSE-301. Most residential tanks have two heating elements but only one runs at a time in normal operation. We review this figure periodically and update it if the source changes; last checked September 2026. Cedrick Reese built this water heater cost calculator and rechecks the wattage figure against the source above.
Frequently asked questions
How many watts does a water heater use?
A standard 40-gallon electric resistance water heater has elements rated at 4,500 to 5,500 watts, according to a DOE-developed appliance energy table reproduced by Virginia Cooperative Extension, though only one element runs at a time.
How much does it cost to run a water heater?
A 4,500-watt water heater running an estimated 3 effective hours a day at the U.S. average rate of about 16.5 cents/kWh costs roughly $2.23 a day, or about $67 a month. Use the calculator above with your own household's usage and rate for a more tailored estimate.
Why does my water heater seem to run so much?
It's reheating water every time hot water is drawn from the tank, plus it periodically cycles on just to offset standby heat loss even when nobody's using hot water, especially on an uninsulated tank. Higher household hot water use and a higher thermostat setting both mean more total runtime.
How can I reduce how much electricity my water heater uses?
Lower the thermostat to around 120°F, insulate the tank and exposed hot water pipes if they feel warm, and fix any dripping hot water faucets, since every drip is water the heater ends up reheating.
This page provides estimates based on typical wattage figures and the numbers you enter, using an estimated 'effective hours' figure to represent cycling rather than continuous running. Actual electricity cost depends on your specific tank size, thermostat setting, and household hot water use.