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Shower Cost Calculator

Find out how much water and energy a shower uses — and what each shower costs you per shower and per year.

Fill a bucket for 10 seconds and multiply the litres by 6. Water-saving heads use 7.6 L/min or less.

The mains water coming into the house — colder in winter.

The mixed water temperature at the shower head.

100 % means all the energy ends up in the water. Use a lower value if you know your heater’s efficiency.

What you pay per kWh including grid fees and taxes (not fixed monthly charges).

Counts only the energy needed to heat the water you use. A real water heater also loses some standby heat, and the electricity price should include grid fees and taxes per kWh (not fixed monthly charges).

About this tool

Enter how long you shower, the flow rate of your shower head, the cold and shower water temperatures and your energy price. The calculator shows the litres (or gallons) used, the kWh needed to heat the water, and the cost per shower and per year.

Frequently asked questions

An 8-minute shower at 10 L/min uses 80 litres. Heating it from 8 °C to 38 °C takes about 2.8 kWh, so at 0.20 per kWh one shower costs about 0.56 — roughly 204 a year if you shower every day.

In the US the federal maximum is 2.5 gallons per minute (9.5 L/min), and WaterSense-labelled shower heads use at most 2.0 gpm (7.6 L/min). To measure yours, hold a bucket under the shower for 10 seconds and multiply the amount by 6.

Heating 1 litre of water by 1 °C takes about 4.186 kJ, which is 1.163 Wh. So kWh = litres × temperature rise × 0.001163: 80 litres heated by 30 °C needs 80 × 30 × 0.001163 = 2.79 kWh.

Cost scales directly with time and flow: cutting a shower from 8 to 5 minutes saves 37.5 %, and swapping a 10 L/min head for a 7.6 L/min one saves 24 %. Lowering the shower temperature from 40 °C to 37 °C with 8 °C cold water saves about 9 %.

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