What size water heater for a family of 2?
With 2 of the 2 showering in the same hour on standard heads, peak demand is 46 gallons: a 30-gallon gas tank covers it, electric needs 40 gallons. Low-flow heads pull the electric answer down to 30 gallons. If all 2 shower back to back, demand hits 46 gallons; the table below covers every version of your mornings.
Every version of the busiest hour, for 2 people
Each row is that many showers in one hour plus one shave and one round of hand dishes, priced in hot gallons off the DOE/AHRI worksheet (20 per standard shower, 13 on a 2.0 GPM low-flow head). The tank shown is the smallest standard size whose first hour rating covers the demand; our FHR figures are ~70% of tank volume plus an hour of recovery, and label values land within a few gallons of them.
| Showers in the hour | Peak demand | Gas tank | Electric tank | Demand, 2.0 GPM heads | Gas | Electric |
|---|---|---|---|---|---|---|
| 1 | 26 gal | 30 gal | 30 gal | 19 gal | 30 gal | 30 gal |
| 2 | 46 gal | 30 gal | 40 gal | 32 gal | 30 gal | 30 gal |
Laundry note: a hot-wash load adds 32 gallons to the hour, which moves every verdict in the table up a row or two. Warm and cold cycles barely register, and that is the cheapest sizing fix there is: wash on warm outside shower hour and buy the smaller tank.
Questions people ask
Is a 50-gallon water heater enough for a family of 2?
Yes, generously. A 50-gallon gas tank delivers about 78 gallons in its first hour and a 50 electric about 55, both past the 46-gallon hour two people can realistically pull. You could buy smaller; nobody regrets a 50.
Do these numbers change with teenagers?
Only in the honest direction. The worksheet's 20-gallon shower is a 10-minute shower on a 2.5 GPM head; a teenager's 25-minute shower is 50 gallons all by itself. If that is your house, count long showers as two.
What about a tankless for a family of 2?
Feasible and usually oversized for the need; a small unit does fine. Size it to simultaneous draw with the tankless calculator, not to this page's gallons.