Water Heating Cost Calculator
Calculate the cost of heating water from gallons used, temperature rise, and electric or gas energy price.
gal
°F
°F
¢/kWh
Result
Daily Cost
$1.43
Monthly Cost
$42.85
Annual Cost
$521.30
Daily Energy Needed
32487 BTU
How to Use the Water Heating Cost Calculator
Enter how many gallons of hot water your household uses per day, the incoming cold water temperature, and the target hot water temperature. Choose electric or gas as your water heater type and enter your energy price to see the daily, monthly, and annual cost of heating that water. Water requires 8.33 BTU per gallon per degree Fahrenheit of temperature rise, which the calculator converts into kilowatt-hours for electric heaters or therms for gas heaters.
Electric: kWh = BTU / 3,412, Cost = kWh × Electric Rate
Gas: Therms = BTU / 100,000, Cost = Therms × Gas Rate
Example
A household uses 60 gallons of hot water per day, with incoming water at 55°F heated to 120°F — a 65°F rise. That's 60 × 8.33 × 65 ≈ 32,487 BTU per day. On an electric heater, that's about 32,487 / 3,412 ≈ 9.52 kWh, costing roughly $1.43 per day at 15¢/kWh, or about $42.90 per month.
Common Use Cases
- Estimating the monthly and annual cost of running a household water heater.
- Comparing water heating costs between electric and gas energy sources.
- Seeing how lowering your water heater's temperature setting affects your energy bill.
FAQs
- Does this account for water heater efficiency losses? No — this calculates the theoretical energy needed to raise the water temperature. Real water heaters have some standby and conversion losses (heat lost through the tank, pilot lights, etc.), so actual costs are typically somewhat higher than this baseline figure.
- How do I find my incoming cold water temperature? It varies by location and season — groundwater temperature commonly ranges from around 40°F in colder climates and winter months to 70°F or more in warmer regions and summer. Check with your local utility or use a thermometer on your cold tap for an accurate reading.
- Would lowering my water heater's temperature save money? Yes — reducing the target temperature lowers the temperature rise needed, which directly reduces energy use. Many water heaters are set higher than necessary; many manufacturers suggest 120°F is sufficient for most households while also reducing scald risk.