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Sizing Explained: Choosing the Right-Sized Water Heater

You know the feeling. You’re taking the last shower of the morning and, what was once steaming two hours ago, is now ice cold. You check your water tank and realize it’s just too small when you bought it before having two teenage children who play sports and eat from every plate in the kitchen. Constant showers, constant clothes washing, and dishwashing lead to cold showers very quickly. It’s time to consider a new water heater, but how many gallons do you need for you and your family?

How many people are in your household is a great place to start calculating gallons. On average, hand washing takes about 2 gallons, Running the dishwasher uses 14 gallons,  bathing/showering per person is 20 gallons, and washing a load of laundry is 30 gallons. So if you’re in a family of four, a 50-gallon water tank should cover all those showers and washings.

Another number to calculate when buying a new water heater is the First Hour Rating (FHR). When a water heater tank is fully heated and waiting for activity, the FHR shows how efficiently the tank can handle refilling and heating in that peak hour of usage where showers and washing happen. For example, if you buy the 50-gallon hot water tank, it should have an FSH of 90, telling you it can provide 90 gallons in that peak period.

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Here’s a general estimate of gallons needed depending on household size:

  • 1 or 2 people — 23 to 36 gallons 30-gallon tank.
  • 2 to 4 people — 36 to 46 gallons 40-gallon tank.
  • 3 to 5 people — 46 to 56 gallons 50-gallon tank electric or 40-gallon gas tank.
  • 5 or more people — over 56 gallons (add 10 gallons per additional person) 80-gallon tank electric or 50 gallon-tank gas tank.

Electric vs. Gas Water Heaters

Electric Water Heater Benefits: Gas Water Heater Benefits:
Lower Purchase Price Typically Lower Operating Costs
Wider Range of Sizes More Energy-Efficient
Safer (no risk of gas leaks) Able To Operate Without Power


These are just some general benefits of between gas and electric water heaters, keep in mind that the price for gas and electric can vary based on your location, so make sure to research which is more cost-effective in your area!

When considering the purchase of a new hot water tank, the cost of heating the water is 20% of your household energy budget. However, if you purchase less than 55 gallons, there is a 4% energy-efficiency boost.  New water heaters 55 gallons or more now have more efficiency (25%-50%) when using a heat pump or condenser to heat the water. According to, an Energy Star certified heat pump water heater could save a family of four more than 50% on energy bills over the water heater’s lifetime. 

Whether you have a small household with less hot water needs or a large home with constant needs, some research and understanding of the SEER on the Energy Guide, you can find the perfect water heater for your needs and save money in the long run.

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We offer water heater replacement, installation, maintenance, and repair as well as tankless water heater services. Ready to upgrade your water tank size? Our professional technicians serve Lexington, Lawrenceburg, Georgetown, and Central KY. Call Turbo Pro Pros today!

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Mention Code: 59CHECKUP when scheduling. $59 System check-up for your HVAC OR Plumbing system Expires 12/31/2023 *Restrictions apply, call for details. Residential only. Offer ends December 31, 2023.
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