How much does an electric water heater cost to run?

The formula

cost = watts × hours ÷ 1,000 × price per kWh

Worked example: 4,500 W × 2.15 h ÷ 1,000 = 9.675 kWh a day. 9.675 kWh × $0.1816 = $1.76 a day, or about $52.71 over 30 days.

How many watts does an electric water heater use?

Most are rated 3,800 to 5,500 W. The element wattage is printed on the rating plate on the side of the tank. For yearly use, the yellow EnergyGuide label is a better guide than the wattage.

• Rheem's residential electric tanks use two 3,800 W, 4,500 W or 5,500 W elements. They are wired non-simultaneous: only one element heats at a time, so the most a 4,500 W tank draws is 4,500 W, not 9,000 W.
• Rheem lists an estimated yearly energy cost of $424 at 12.00¢/kWh for its 50-gallon 0.92 UEF tanks, which works out to about 3,533 kWh a year, or 9.68 kWh a day. That equals a 4,500 W element running about 2.15 hours a day, which is our default.
• The same Rheem chart lists $293 a year (about 2,442 kWh) for 30-gallon tanks sized for 1 to 2 people, $104 (about 867 kWh) for a 50-gallon hybrid heat pump model at 3.75 UEF, and $149 (about 1,242 kWh) for an 80-gallon heat pump model at 4.00 UEF.
• Models with 4,500 W and 5,500 W elements carry the same yearly cost in Rheem's chart. A bigger element heats the tank back up faster after a long shower; it does not use more energy for the same hot water.
• Point-of-use mini tanks (2.5 to 20 gallons) for a single sink are much smaller loads: Rheem rates them at 1,440 to 2,000 W.
• UEF (uniform energy factor) is DOE's efficiency rating for water heaters; higher is better. ENERGY STAR certifies integrated heat pump water heaters at 3.30 UEF or more and does not certify standard electric tanks.

Cost at different electricity prices

Per month (30 days) and per year (12 such months). Real use is usually seasonal. Average residential prices for August 2026 from the same EIA table. Your utility's rate, including delivery charges, may differ. Check the price per kWh on your bill.

Ways to pay less

1. Set the thermostat to 120°F DOE calls 120°F safe for most people, and CPSC urges every household to lower water heaters to that setting to prevent scalds. Most electric tanks have two thermostats, one per element, and both need the same setting. Turn the breaker off before you open the access panels.
2. Insulate a tank that is warm to the touch DOE says an insulating jacket on a warm tank can cut water heating costs by 7 to 16% a year. On a standard 50-gallon tank at $52.71 a month that is about $3.69 to $8.43 a month. Follow the maker's instructions and keep the thermostat panels and relief valve uncovered.
3. Insulate the pipes and under the tank DOE puts hot water pipe insulation at another 3 to 4% a year, and for electric tanks, insulation under the tank at 4 to 9% of water heating energy.
4. Use less hot water Low-flow showerheads and aerators cut hot water use directly. DOE says one drip a second from a leaking faucet wastes 1,661 gallons a year and can cost up to $35, so fix hot-side leaks first.
5. Flush sediment, and plan a heat pump model for replacement DOE suggests draining a quart from the tank every 3 months to clear sediment. When the tank is due for replacement, a heat pump model is the biggest saving: DOE cites ENERGY STAR's figure of 70% less electricity than a standard electric tank. ENERGY STAR says it needs a space that stays between 40 and 90°F with about 1,000 cubic feet of air around it.

Safety. CPSC says most adults suffer third-degree burns after 2 seconds in 150°F water, 6 seconds at 140°F and 30 seconds at 130°F, and urges a setting of 120°F. Young children and older adults are most at risk, so test bath water by hand. To adjust an electric tank yourself, avoid using hot water for 2 hours beforehand and switch off the breaker before opening the thermostat covers.