Water Heater Calculator

A family of 2-3 needs a 40-50 gallon tank or 5-7 GPM tankless. Family of 4-5 needs a 50-80 gallon tank or 7-9 GPM tankless. Base sizing on peak hour demand — the first hour rating should exceed your busiest hour's hot water usage.

Tankless heaters cost 2-3x more upfront but save 20-30% on water heating energy annually and last 20+ years (vs 10-15 for tank). They pay for themselves in 8-12 years. Best for homes with consistent moderate demand rather than extreme peak usage.

Heat pump water heaters are the most energy-efficient (2-3x more efficient than standard electric), saving $200-400/year. Solar water heaters save the most in sunny climates. For gas, tankless condensing units achieve 95%+ efficiency.

Using the Water Heater Calculator is simple: visit the tool page, enter your data or input into the provided fields, and get instant results. Follow the controls on the page. Some functions require sign-in or a paid plan; see Pricing for limits.

The Free plan includes 10 tool uses per day. Some features require an account or a paid plan. Check the controls on the tool page and Pricing for the applicable limits.

The Water Heater Calculator returns results based on the inputs and the tool methodology. Check assumptions, units and source dates. Treat projections as estimates. For critical decisions, always consult a qualified professional.

Yes, the Water Heater Calculator is fully responsive and works perfectly on smartphones, tablets, and desktop computers. Simply open NexTool in your mobile browser and navigate to the tool — no app download required.