Systems
Water Heater Sizing Calculator
Tell us how many people live in the home. We'll suggest a tank size and a tankless flow rate.
At a glance
- What you enter
- People in the household
- Accuracy
- Rule of thumb
30-40 gallon tank, or 3-5 GPM tankless
For that household, a 30-40 gallon tank or a tankless unit rated around 3-5 GPM usually keeps up. Lots of simultaneous showers or a big soaking tub pushes it higher.
Treat this as a guide rather than a final spec. Simultaneous demand (two showers plus the dishwasher), incoming water temperature, and fixture flow rates all matter, and a plumber sizes tankless by peak GPM.
Systems
Oversized is its own kind of broken
An air conditioner with too much capacity short-cycles, never pulls the humidity out, and wears itself down early. In a Carolina summer that matters more than the raw tonnage.
How this is worked out
No hidden fudge factor. This is the whole calculation.
- You enter people in the household.
- That runs through a rule of thumb calibrated for the North Carolina climate.
- It is a starting point for the conversation, not the calculation a licensed pro performs.
Common questions
- Water Heater Sizing: how do I choose the right size?
- Tell us how many people live in the home. We'll suggest a tank size and a tankless flow rate. It's a rule-of-thumb starting point; a licensed pro does the exact calculation for your home.