Water Heater Running Cost Calculator

Work out water heater running cost instantly with clear inputs, formula shown and shareable results.

About Water Heater Running Cost Calculator

Every gallon of hot water needs 8.33 BTU per degree Fahrenheit of rise. Daily volume times rise gives the useful heat, dividing by 3412 converts to kilowatt hours and dividing by efficiency accounts for what the appliance wastes. Multiplying by the tariff gives the running cost.

Formulas

Energy per day

kWh = gallons x 8.33 x ΔT / (3412 x efficiency)

Annual cost

Cost = daily kWh x price x 365

Worked example

With the default values below, Water Heater Running Cost Calculator returns Annual water heating cost of $610.19. Change any input above and every figure here is recalculated in your browser.

Inputs used

Hot water used per dayminimum 1 gal: 60 gal
Temperature riseminimum 1 °F: 70 °F
Energy priceminimum 0.001 per kWh: 0.15 per kWh
Heater efficiencyaccepts 20–100 %: 92 %

Results

Annual water heating cost: $610.19
Daily cost: $1.672
Daily energy use: 11.14 kWh
Annual energy use: 4,068 kWh

Step by step

1Values used
2Energy per day
3Annual cost
4Annual water heating cost= 610.19
5Daily cost= 1.672
6Daily energy use= 11.14 kWh
7Annual energy use= 4,068 kWh

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is the Water Heater Running Cost figure worked out?

kWh = gallons x 8.33 x ΔT / (3412 x efficiency). Every gallon of hot water needs 8.33 BTU per degree Fahrenheit of rise.

Does this include standby loss?

No. It covers only the water actually drawn. A poorly insulated tank can add another 10-15 percent for heat that leaks away between draws.

What values do I need to enter?

This calculator takes 4 inputs: Hot water used per day, Temperature rise, Energy price, Heater efficiency. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.