Water Heater Size Calculator – What Tank Size? | CalcLoft
Find out what size water heater your household needs.
What size water heater do I need?
Tank size depends on people, bathrooms and peak usage:
| Household | Tank size |
|---|---|
| 1-2 people | 30-40 gallons |
| 2-3 people | 40 gallons |
| 3-4 people | 40-50 gallons |
| 4-5 people | 50-60 gallons |
| 5-6 people | 60-80 gallons |
First-hour rating matters more
The label's First Hour Rating (FHR) tells you how much hot water the tank can deliver in a busy hour. For a family of 4 with 2 baths, look for an FHR around 60-70 gallons — that beats a bigger tank with a low FHR.
Fuel type
- Gas: heats faster, recovers quicker, cheaper to run in most areas
- Electric: no venting needed, but slower recovery — size up one tier
Water heater calculator FAQ
What size water heater for a family of 4?
50 gallons (gas) or 60+ gallons (electric) with a good first-hour rating.
40 or 50 gallon?
40 suits 2-3 people; choose 50 for 4+ or high usage — the cost difference is small.
Tankless instead?
Tankless units heat on demand — great for small households or endless hot water, but higher upfront cost.
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