Understand your estimate
How to use this result
For a point-of-use electric shower, selected electrical kW times minutes gives shower energy. Add an optional measured-flow water charge separately, and keep power, flow and shower count fixed in a shorter-duration scenario.
Method reviewed · Calculation methods · Evidence and source policy
Find the right inputs
Selected electrical input
kW
A mixer shower or pump-only rating needs another heat-source boundary.
Routine
Minutes/shower, showers/day and use days
The total selected shower duration must fit within one day.
Optional variable water charge
Measured litres/minute and matching billed price
Use the same operating setting; do not add a second heating-energy charge.
The calculation
Shower kWh = input kW × minutes ÷ 60. Period electricity = shower kWh × shower count × tariff. Water cost uses flow × minutes × count with the matching volume price.
A worked arithmetic example
Illustrative arithmetic: 9 kW for eight minutes uses 1.2 kWh, or $0.24 of electricity at $0.20/kWh. Four showers/day over 365 days cost $350.40 for electricity; optional water charges are additional.
What the estimate can tell you
Changing selected power or inlet conditions can change the useful comparison. A shorter-duration result is conditional on the entered fixed inputs and is not a universal household saving.
Questions about this calculation
Can I use the tool for a shower supplied from a hot-water tank?
Not with the point-of-use input method. Use an appropriate water-heater energy boundary, and retain any separately measured pumping electricity if relevant.
What if my water bill has no per-volume charge?
Leave water cost excluded or enter a known zero variable price if that is appropriate to your bill. Fixed fees are not avoided by one shorter shower.