Body Care Calculators
Shower and bath cost calculator.
Work out what a shower or a bath costs in heating energy and water, and what a year of them adds up to, using your own flow, temperature and prices. Runs in your browser.
Your shower and bath
Cost
Fill the form and press Calculate.
Worked example
A 10 minute shower at 2.5 gal/min uses 25 gallons (94.6 L). Heating it by 50 °F takes 25 × 8.34 lb × 50 = 10,425 Btu = 3.06 kWh. At $0.15 per kWh and 100% efficiency that is $0.46, plus $0.15 of water at $6 per 1,000 gallons: $0.61 a shower. Seven a week is 364 a year, $221.53. A 40 gallon bath at the same temperature costs $0.97, which is 1.6 times the shower; the shower and the bath cost the same at 16 minutes of running water.
How it works
EIA defines one Btu as the heat needed to raise one pound of water by one degree Fahrenheit, and gives 1 kWh = 3,412 Btu. USGS gives the density of water as roughly 1 gram per millilitre, so a gallon is about 8.34 lb. That works out to 0.001163 kWh per litre per °C, which is the figure the tool uses (heating energy = litres × °C rise × 0.001163 ÷ efficiency). Cost = kWh × your price, plus litres of water × your water price.
EPA WaterSense says standard showerheads use 2.5 gallons per minute and WaterSense-labelled ones must use no more than 2.0. Your actual flow, time, temperatures, tub fill, prices and heater efficiency are your own numbers; none of them is a published average here. Pipe heat loss and warm-up water that runs down the drain are not counted.
Sources and basis (opened 2026-10-08): U.S. Energy Information Administration, British thermal units (Btu); US EPA WaterSense, Showerheads; USGS, Water Density.
FAQ
How much does a shower cost?
It depends on your flow, time, water temperature and prices. At 10 minutes, 2.5 gal/min, a 50 °F rise, $0.15 per kWh and $6 per 1,000 gallons, a shower costs about $0.61 (3.06 kWh of heating and 25 gallons of water).
Is a bath more expensive than a shower?
It depends on the tub fill and how long you shower. With a 40 gallon bath against a 10 minute shower at 2.5 gal/min, the bath costs about 1.6 times as much, and they cost the same at 16 minutes of running shower.
How much water does a showerhead use?
EPA says standard showerheads use 2.5 gallons per minute, and WaterSense-labelled models must use no more than 2.0 gpm. Time your own shower and measure your flow for a real figure.
How is the heating energy worked out?
One Btu raises a pound of water one degree Fahrenheit (EIA) and one kWh is 3,412 Btu. A gallon is about 8.34 lb, so 25 gallons heated 50 °F needs 10,425 Btu, or 3.06 kWh at 100% efficiency.
What if I heat water with gas or a heat pump?
Set the efficiency to match: lower for gas, above 100% for a heat pump, and enter the gas price converted to dollars per kWh (1 therm = 29.31 kWh, since a therm is 100,000 Btu per EIA).
Disclaimer
A cost estimate from numbers you enter, not a bill. Heat losses in pipes and tanks and water run before the shower warms up are not included. Not advice on water temperature; keep shower and bath water at a safe temperature, especially for children and older adults.