Water Heater Sizing Calculator

Size a tank water heater for your home based on household size and hot water demand. Compare tank sizes from 30 to 80 gallons across electric, natural gas, propane, and heat pump fuel types with estimated annual operating costs.

Fuel Type

People in Household

Number of Bathrooms

Peak Hour Demand (gal)

Incoming Water Temp (°F)

Desired Output Temp (°F)

Pricing (edit to match local rates)

30 Gallon Tank ($)

40 Gallon Tank ($)

50 Gallon Tank ($)

65 Gallon Tank ($)

80 Gallon Tank ($)

Natural Gas ($/therm)

Peak Hour Demand

68 gal

4 people, 2 bathrooms

Temperature Rise

70°F

50°F → 120°F

Est. Annual Fuel Cost

$304.95

Natural gas

Recommended Size

80 Gallon Tank

First-year cost: $1,404.95

Tank Size	Demand Status	First-Year Cost
30 Gallon Tank (undersized)	Too small	$754.95
40 Gallon Tank (undersized)	Too small	$854.95
50 Gallon Tank (undersized)	Too small	$1,004.95
65 Gallon Tank (undersized)	Too small	$1,204.95
80 Gallon TankBest value	Meets demand	$1,404.95

Recommended: 80 Gallon Tank at $1,404.95 first-year costBased on a peak hour demand of 68 gallons, the 80 gallon tank is the most cost-effective option that meets your household needs. Annual operating cost is estimated at $304.95 for natural gas.

Large Tank: Higher Standby LossesAn 80-gallon tank holds more hot water but also has higher standby heat losses, especially for electric and gas models. If your peak demand is close to 65 gallons, a 65-gallon tank may save on both purchase price and operating costs.

This is an estimate for planning purposes. Actual water heater performance depends on local water conditions, usage patterns, installation factors, and fuel costs. First-hour ratings vary by manufacturer and model. Consult a licensed plumber for a site-specific recommendation.