Water Heater Fuel Type Cost Comparison Calculator
Compare the estimated annual operating costs of different water heater fuel types based on your household usage and local energy rates.
Formula
Annual Heat Load (BTU):
Q = Gallons/year × 8.33 lb/gal × 1 BTU/(lb·°F) × (Tout − Tin)
Annual Fuel Consumption:
Fuel Input (BTU) = Q ÷ UEF
Annual Cost:
Cost = Fuel Input (BTU) ÷ Energy Content per Unit × Rate per Unit
Energy Content: Electricity = 3,412 BTU/kWh | Natural Gas = 100,000 BTU/therm | Propane = 91,452 BTU/gal | Fuel Oil = 138,500 BTU/gal
Assumptions & References
- Hot water usage: 18 gallons per person per day (U.S. DOE baseline for storage water heaters).
- Water density: 8.33 lb/gallon; specific heat of water: 1 BTU/(lb·°F).
- UEF (Uniform Energy Factor) values are typical mid-range figures per DOE/ENERGY STAR 2023 standards: Electric Resistance 0.92, Gas Storage 0.64, Propane Storage 0.62, Fuel Oil 0.62, Heat Pump 3.50, Tankless Gas 0.82, Tankless Electric 0.99.
- Default energy rates approximate 2024 U.S. national averages (EIA): electricity $0.13/kWh, natural gas $1.20/therm, propane $2.80/gal, fuel oil $3.50/gal.
- Standby losses, installation costs, and maintenance are not included in this operating cost estimate.
- References: U.S. DOE Energy Efficiency & Renewable Energy (EERE), EIA Monthly Energy Review, ENERGY STAR Water Heater Program.