Water heater sizing Last reviewed June 30, 2026
What Size Water Heater for a 1-2 Person Household?
By the WhatSize editorial team 4 min read Standards-reviewed
A 1-2 person household needs a 30-40 gallon storage tank water heater. For tankless, a 4.3 GPM model like the EcoSmart ECO 18 is sufficient. Consider a 40-gallon if you take back-to-back showers.
Sizing for Small Households
For 1-2 people, water heater sizing is straightforward. The DOE First Hour Rating (FHR) standard recommends 30-40 gallons for small households. A 30-gallon tank provides about 30-35 gallons of hot water in the first hour — enough for 1-2 showers plus hand washing. A 40-gallon tank gives you more headroom for back-to-back showers or occasional guests.
If you're considering tankless, a unit rated for 4.3 GPM (gallons per minute) like the EcoSmart ECO 18 can handle one shower and a sink simultaneously — more than enough for a couple.
Top picks for this size
These Amazon-available picks meet the calculated spec. For region-specific or licensed contractor-installed options, consult a local professional. See our Disclaimers.
Best Options for 1-2 Person Households
- Storage tank: Rheem Performance 40 Gal (~$459) — best overall value, 6-year warranty
- Tankless electric: EcoSmart ECO 18 (~$499) — compact, 4.3 GPM, self-modulating
- Gas tankless: Rinnai RU160iN (~$1,299) — 7.5 GPM if you plan for future needs
Frequently asked questions
What size water heater for a 1-2 person household?
Yes, 30 gallons is usually sufficient for 2 people who stagger their showers. If you both shower in the morning, consider 40 gallons to avoid running out of hot water.
Should I get a tankless for a small household?
Tankless makes sense if you have natural gas and want unlimited hot water. The upfront cost is higher ($500-1,300 vs $400-500 for tank), but you save on energy costs over time.
You might also need
More water heater sizing guides
- What Size Water Heater for a 3-4 Person Household?
- What Size Water Heater for a Family of 5?
- Tank vs Tankless Water Heater: Which Size Is Right?
- What Size Water Heater for Electric vs Gas Homes?
- Water Heater FHR Chart: First Hour Rating by Household Size
- Tankless Water Heater GPM Chart by Household Size
- Water Heater UEF Rating Explained: Energy Factor vs FHR Chart
- What Size Water Heater for a 2-Bathroom House?
- 40 vs 50 Gallon Water Heater: Which Size Do You Need?
Still choosing between sizes? Compare: tank vs tankless