How to use this calculator
Select your household size, current water heater type, and the type you're considering. Enter your local electricity and natural gas rates for the most accurate comparison. The calculator estimates daily hot water usage at about 20 gallons per person per day, which is the U.S. average.
The default energy rates ($0.16/kWh for electricity, $1.20/therm for gas) are approximate national averages. Check your utility bills for your actual rates, they can vary significantly by region and plan.
Water heater types compared
- Gas Tank (EF 0.60): The most common type. Low upfront cost, moderate operating cost. Stores 40-50 gallons and maintains temperature continuously, which causes standby heat loss.
- Electric Tank (EF 0.93): More efficient than gas tanks but electricity is often more expensive than gas. Simple installation, widely available, and no venting required.
- Gas Tankless (EF 0.82): Heats water on demand with no standby losses. Higher upfront cost but lower operating cost than gas tanks. Can last 20+ years.
- Electric Tankless (EF 0.99): Very efficient on-demand heating. Requires significant electrical capacity and may need a panel upgrade. Best for smaller households or point-of-use applications.
- Heat Pump (EF 2.0+): The most efficient option. Moves heat from surrounding air into the water, using a fraction of the energy of direct heating. Eligible for federal tax credits up to $2,000.
Understanding efficiency ratings
The Energy Factor (EF) measures how efficiently a water heater converts energy into hot water. An EF of 0.60 means 60% of the fuel's energy goes into heating water, while 40% is lost. Heat pump water heaters achieve EF ratings above 2.0 because they move heat rather than generate it directly.
The newer Uniform Energy Factor (UEF) is gradually replacing EF as the standard metric. UEF ratings tend to be slightly different from EF but follow the same principle: higher numbers mean better efficiency. The values in this calculator use EF for simplicity and broad comparability.
Typical water heater lifespan
Tank water heaters (gas or electric) typically last 10-15 years. Tankless models can last 20 years or more with proper maintenance, including periodic descaling. Heat pump water heaters fall in between at about 13-15 years, though the technology is improving rapidly.
When comparing costs, factor in how many replacement cycles you'll need over a longer period. A tankless unit that lasts 20 years might outlast two tank water heaters, making the total cost comparison even more favorable despite the higher upfront price.
Frequently asked questions
Which type of water heater is cheapest to operate?
Heat pump water heaters are typically the cheapest to operate, with energy factors of 2.0 or higher. They cost 2-3x less to run than conventional electric tank heaters, though gas tankless units can be competitive in areas with low natural gas prices.
How long does a tankless water heater last compared to a tank?
Tankless water heaters typically last 20+ years with proper maintenance, compared to 10-15 years for traditional tank water heaters. This longer lifespan helps offset the higher upfront cost of tankless units.
Is it worth switching from gas to a heat pump water heater?
It depends on your local energy rates. In areas with affordable electricity and expensive gas, a heat pump water heater can save $200-400 per year. With federal tax credits, the payback period can be as short as 3-5 years.
How much hot water does the average household use per day?
The average American uses about 20 gallons of hot water per day. A family of four uses roughly 80 gallons daily, covering showers, laundry, dishwashing, and other household uses.