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Electric Water Heater Cost Calculator

Estimate what your electric water heater costs per day, month and year — often one of the biggest items on an electric bill.

Quick answer

A 4,500 W electric tank heating for 3 hours a day uses 13.5 kWh — about $2.30 a day or $69 a month at $0.17/kWh. Hot water also drives most of the cost of washing and dishwashing.

  • Free
  • No sign-up
  • Energy
  • Updated October 2026
W

On the label or manual. 1 kW = 1000 W.

%

Share of time it actually draws full power. AC and fridges cycle on and off; lights and TVs are 100%.

Find it on your bill (cents ÷ 100).

Cost per month (30 days)

$68.85

Cost per day
$2.30
Cost per year
$837.68
Cost per hour of use
$0.77
Energy per day
13.5 kWh
Energy per month
405 kWh
Show the working
  1. 4,500 W × 3 h × 100% × 1 ÷ 1000 = 13.5 kWh/day
  2. 13.5 kWh × $0.17 = $2.30 per day

About the Electric Water Heater Cost calculator

A standard 40-gallon electric tank has heating elements rated around 4,500–5,500 W (EPA figures). The element only runs when the tank needs reheating — after showers, laundry and dishwashing, and to make up standby heat loss — so the key input is how many hours a day it actually heats.

The default is a 4,500 W element running 3 hours a day in total, about 13.5 kWh a day, which is in line with a busy household. Lowering the thermostat to around 120 °F (49 °C), insulating hot pipes and using less hot water all cut those hours.

How to use it

  1. Enter the element wattage from the tank label.
  2. Estimate total heating hours per day (2–4 for a typical family).
  3. Keep 100% load — the element is either on or off.
  4. Enter your price per kWh.

The formula

Daily cost = Watts × Heating hours ÷ 1000 × Price

  • Heat-pump water heaters deliver the same hot water for a fraction of the electricity.

Worked example

A 4,500 W tank heating 3 hours a day

  1. 4,500 W × 3 h = 13.5 kWh per day.
  2. At $0.17/kWh: about $2.30 per day.
  3. About $68.85 per month.

Frequently asked questions

How long does an electric water heater run each day?

It depends on hot-water use. A household of 3–4 commonly has 2–4 hours of element run time a day; a heavy-use home can be higher.

Does turning down the temperature save money?

Yes. Around 120 °F (49 °C) is a common recommendation; each step down reduces standby losses and the energy needed to reheat the tank.

Is a heat-pump water heater cheaper?

Typically it uses well under half the electricity of a standard electric tank for the same hot water, though it costs more to buy.

Results are estimates for planning — check critical figures with a professional or the official source.

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