Heat Pump Water Heater Calculator
See the right tank size and how much a heat pump water heater saves vs your current one.
What size tank do you need?
Heat pump water heaters have strong first-hour ratings, so you rarely need to upsize. A common guide: 1–2 people → 50 gallons, 3–4 → 65–66 gallons, 5+ → 80 gallons. If you have a big soaking tub or simultaneous showers, size up one step.
How much a heat pump water heater saves
A heat pump water heater (HPWH) moves heat from the surrounding air into the tank instead of using a resistance element, so it uses roughly one-third the electricity (UEF around 3.5 vs 0.9). For a family of four replacing an electric resistance tank, that's typically $300–$550 per year. Versus gas, savings depend on your local gas vs electricity prices.
Is it worth it?
If you're replacing an electric resistance tank, almost always — the energy savings plus incentives usually pay back in a few years. They cost more upfront and need some surrounding air volume (about 700–1,000 cu ft) or a ducting kit in a small closet.
Frequently asked questions
What size heat pump water heater do I need?
1–2 people → 50 gallons, 3–4 → 65–66, 5+ → 80. Heat pump water heaters have strong first-hour ratings, so you rarely need to upsize.
How much does a heat pump water heater save?
Versus electric resistance, often $300–$550 per year for a family of four, because it uses roughly one-third the electricity (UEF ~3.5).
How much does a heat pump water heater cost?
Typically $1,500–$3,000 installed before any state or utility rebates — more than a standard electric tank, but the energy savings usually pay it back in a few years.
Do heat pump water heaters work in cold spaces?
They pull heat from the surrounding air, so they work best in a space that stays above ~40°F with some air volume (a garage or basement). In a small closet they may need a duct kit, and most have a backup resistance mode for cold snaps.
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⚠️ Rule-of-thumb estimate, not a substitute for a professional Manual J load calculation. Based on US DOE / ENERGY STAR guidance.