The short answer

A point-of-use electric shower uses selected electrical kW multiplied by shower minutes divided by 60. Multiply by shower count and your tariff. Water and wastewater can be added separately using measured flow and a variable rate; a mixer shower needs a calculation for its own heat source.

Use the electric showers calculator
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First identify which shower you have

This method applies to a shower that heats cold water electrically at the point of use. A mixer supplied by a boiler or hot-water cylinder has a different energy boundary. The small electrical rating on a shower pump is not the energy needed to heat all its water.

Use the actual selected heating input. A maximum nameplate rating can differ from a lower power selection. If the input changes during use, suitable measured electricity is preferable to assuming maximum draw throughout.

Price one complete shower

An illustrative 9 kW input for eight minutes uses 9 × 8 ÷ 60 = 1.2 kWh. At an assumed $0.20/kWh, that is $0.24 of electricity per shower. The tariff and selected power are example inputs, not national values or a product recommendation.

Four such showers per use day across 365 days mean 1,460 showers and 1,752 kWh, costing $350.40 for electricity. This is a selected routine, not a forecast of a particular household’s behaviour.

Add water only when its charge is known

Suppose measured flow is 6 litres/minute at the same operating setting. Eight minutes uses 48 litres. At an illustrative combined variable water and wastewater rate of $4/m³, water costs 48 ÷ 1,000 × 4 = $0.192 per shower.

The included total becomes $0.432 per shower and $630.72 for 1,460 showers. Water alone contributes $280.32. Fixed water charges remain outside the calculation. A blank water price stays excluded; it does not become free water.

Use the exact volume unit on a water bill. One cubic metre is 1,000 litres. US and Imperial gallons differ, so the calculator labels them separately. If water and wastewater use different billed volumes, establish a consistent effective variable rate before adding them together.

Explore a shorter duration on the same basis

Keeping 9 kW, 6 litres/minute and all other inputs constant, six-minute showers use 0.9 kWh and 36 litres. The included electricity-plus-water cost is $0.324 per shower, or $473.04 in the stated annual routine. The difference is $157.68.

That is a duration scenario, not a claim that every shower can save the same amount. Changing a power setting, water temperature, incoming supply or flow can change the comparison. The calculator keeps the entered values fixed so its assumptions remain visible.

Keep heating costs on one boundary

Do not add a separate hot-water-heating charge to this point-of-use electrical input: that would price the same heating twice. For a cylinder-supplied mixer, use the water-heater tool on an appropriate measured boundary instead.

Record how you obtained power, flow, duration and shower count. The electric-shower calculator preserves them in a saved or shared scenario. Compare actual periods with your bill only when dates and energy boundaries agree.

Match a mixed week to the entered frequency

Suppose an illustrative household takes two showers on each of five weekdays and six on each of two weekend days. The total is 22 showers, not 28. At the earlier 1.2 kWh per shower and $0.20/kWh, this constructed week uses 26.4 kWh and costs $5.28 for electricity.

For a seven-day scenario, an average of 22 ÷ 7 showers/day reproduces that count, or calculate the two groups separately. This does not assume that the same frequency continues all year. Use an appropriate day count for the period you are budgeting.

Keep power and flow from the same setting

A selected electric input, measured flow and timed shower should describe the same operating conditions. Pairing maximum flow from one setting with power from another can create a misleading water-plus-electricity total.

The water-use source provides broader household context. Our shorter-duration comparison keeps the entered input and flow fixed; it does not infer how temperature controls or changing supply conditions affect a particular shower.