Water Heater Efficiency Calculator

Compare water heater types by efficiency factor and calculate annual operating cost for heating water.

Save
gallons
degrees F
ratio
USD/therm or USD/kWh

Annual Water Heating Cost

436 USD

Daily Energy Needed27,163 BTU
Monthly Cost36 USD
Heat Pump WH Savings (UEF 3.5)321 USD

Annual Water Heating Cost vs Daily Hot Water Usage

View formula & how it works →

How to Calculate Water Heater Costs

Water heating is typically the second largest energy expense in a home (14-18% of energy bills).

Formula

Daily BTU = Gallons * Temp Rise * 8.33

Annual Energy = Daily BTU * 365 / Energy Factor

Energy Factors

  • Standard gas: 0.60-0.70
  • High-efficiency gas: 0.80-0.98
  • Electric resistance: 0.90-0.95
  • Heat pump water heater: 2.0-4.0

    • Example Calculation

    50 gal/day hot water, 60F temp rise, 0.92 energy factor, $0.15/kWh.

    1. 01Daily BTU: 50 * 60 * 8.33 = 24,990 BTU
    2. 02Daily energy with EF: 24,990 / 0.92 = 27,163 BTU
    3. 03Annual energy: 27,163 * 365 = 9,914,526 BTU
    4. 04Annual cost: 9,914,526 / 3,412 * $0.15 = $436

    Frequently Asked Questions

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