Heating

Water Heating Cost Calculator

Heating water is one of the biggest energy uses in most homes. This calculator estimates the daily and yearly cost of heating your hot water.

Your details

L

A shower uses ~50 L; a bath ~80 L.

°C

How much the water is heated (e.g. 15°C inlet to 50°C = 35°C rise).

%

Electric ~100%, heat-pump >200%, gas ~80%.

$ /kWh

Results

Energy used per day
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Cost per day
—
Estimated yearly cost
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Last updated June 30, 2026. Results update automatically as you type.

How it works

Energy (kWh) = litres × temperature rise × 4.186 ÷ 3600, then divided by efficiency ÷ 100. (4.186 kJ is the energy to heat 1 litre of water by 1°C; 3600 kJ = 1 kWh.) Daily cost = energy × rate; yearly cost = daily × 365.

Frequently asked questions

How can I cut water heating costs?

Use less hot water (shorter showers, efficient shower heads), lower the thermostat slightly, insulate the tank and pipes, or switch to a heat-pump water heater which is 2–3× more efficient.

Why can efficiency be over 100%?

Heat-pump water heaters move heat rather than create it, delivering more heat energy than the electricity they use — so their effective efficiency is 200–300%.

What temperature should my water be?

Around 50–60°C balances comfort, energy use and safety (hot enough to limit bacteria, not so hot it scalds or wastes energy).

These calculators provide general estimates for educational purposes only and are not financial advice. Real-world results depend on factors not captured here. Verify figures independently before making any purchase or financial decision.

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