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Get water heater size recommendations based on household size and peak demand.
A water heater sizing calculator recommends the right tank capacity or tankless GPM rating based on household size, bathrooms, and peak hot water usage.
| Household | Tank | Tankless |
|---|---|---|
| 1–2 people | 30–40 gal | 3–4 GPM |
| 2–3 people | 40–50 gal | 5–6 GPM |
| 3–4 people | 50–60 gal | 6–8 GPM |
| 4–5 people | 60–80 gal | 8–10 GPM |
| 5+ people | 80+ gal | 10+ GPM |
Formula
Peak Hour Demand = Number of People × 12 gallonsPeople = number of household members
12 gallons = average hot water use per person during peak hour
Worked Example
Family of 4, 2 simultaneous showers + dishwasher
Did you know? Water heating is the second-largest energy expense in U.S. homes, accounting for about 18% of total energy costs — roughly $400–$600 per year (source: U.S. DOE).
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