How much does an electric water heater cost?

What changes the cost of a water heater?

The quick answer is power multiplied by time and your electricity rate—but the right input depends on the appliance. Wattwise starts this calculator with a representative estimate, not a manufacturer-specific claim. Replace defaults with measured, label, or bill values wherever possible.

• Daily hot-water volume
• Starting and target temperatures
• Tank or instant-heater efficiency
• Standing heat loss and schedule
• Showers and occupants

Example water heater running costs

These examples use United Kingdom unit rate and the typical schedule shown in the calculator. Electricity tariffs vary by provider, tier, time, tax, and subsidy, so replace the rate with the value on your bill.

Ways to reduce this appliance’s electricity cost

Savings depend on comfort, safety, usage, and the equipment you already own. Model a change before buying a replacement, and verify high-cost appliances with a meter or label value.

1. Heat only the volume you expect to use.
2. Compare a 5°C lower set point while maintaining safe hygiene guidance.
3. Use a timer to avoid reheating an unused storage tank all day.

How Wattwise calculated this estimate

For the default inputs, Wattwise estimates $13.44 per month and 67.2 kWh at the global reference rate. The active formula is: litres × 4.186 kJ/kg°C × temperature rise ÷ 3,600 ÷ efficiency.

The displayed range widens when power, duty cycle, weather, or tariff data are estimates. It narrows when you provide measured energy, an official annual kWh value, or a per-cycle energy label. Fixed charges are not allocated to one appliance unless you explicitly create a household bill allocation.