Water Heater Size Calculator
Calculate the right water heater size based on number of bathrooms, people, and fixtures. Supports tank and tankless systems.
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Warm/hot wash cycles use hot water
Tank heaters are sized by gallons; tankless by GPM and temp rise
°F
Groundwater temp — 40-50°F in cold climates, 60-70°F in warm climates
First-Hour Demand
62.00gallons
4 shower(s): 40 gal + Kitchen sink: 4 gal + Hand washing: 8 gal + Dishwasher: 6 gal + Clothes washer (50% overlap): 3.5 gal
Recommended Tank Size
65.00gallons
Match to a tank with this first-hour rating (FHR) or higher
Temperature Rise Needed
60.00°F
From 50°F inlet to 110°F delivery
Assessment
Moderate demand — a 65-gallon tank should cover your peak hour. If your household staggers showers, you could get by with a smaller unit. Check the FHR, not just tank size.
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