Water heater operating cost calculator
Enter your utility rates and household size to estimate what each water heater category costs to run per year. The math uses each category's median certified Uniform Energy Factor (UEF) — the same efficiency figure behind the running-cost line on our model pages.
| Category | Assumed UEF | Energy / year | Cost / year |
|---|
Assumptions (all documented, all adjustable in your head)
- Hot water use: 18 gallons per person per day. The DOE test's "medium" draw pattern (55 gal/day) corresponds to roughly a three-person household.
- Temperature rise: 67 °F (58 °F inlet → 125 °F setpoint — the DOE UEF test conditions). Colder groundwater or hotter setpoints raise every number proportionally.
- Physics: heating 1 gallon by 1 °F takes 8.34 BTU. Annual energy in = gallons/day × 365 × 8.34 × 67 ÷ UEF, converted at 3,412 BTU/kWh for electric and 100,000 BTU/therm for gas.
- Efficiency: median certified UEF per category from our live dataset — heat pump 3.7, gas tankless 0.95, gas storage 0.89 — plus an assumed 0.92 for a standard (non-certified) electric resistance tank. Individual models vary; check the model page for the exact figure.
These are planning estimates, not bills. Real usage differs from the DOE draw pattern, heat pump output drops in cold installation spaces, gas storage models certified by ENERGY STAR are more efficient than the builder-grade tanks they replace, and purchase + installation costs are a separate question — see heat pump vs gas and the operating-cost guide for the fuller economics.
Browse the categories: heat pump · gas tankless · gas storage