Water heater specs, efficiency comparisons, and sizing by household

Structured specifications for all 1084 ENERGY STAR certified water heaters across 61 brands — heat pump (hybrid electric), gas tankless, and gas storage. Efficiency (UEF), first-hour rating, flow rate, annual energy use, and the running cost math done for you. Data straight from the U.S. EPA's certified water heater datasets.

Browse water heaters

• All 1084 certified water heaters
• Heat Pump (Hybrid Electric) Water Heaters
• Gas Tankless Water Heaters
• Gas Storage Water Heaters
• 40-Gallon Water Heaters
• 50-Gallon Water Heaters
• 65-Gallon Water Heaters
• 80-Gallon Water Heaters
• 4-GPM Gas Tankless Water Heaters
• 5-GPM Gas Tankless Water Heaters
• 6-GPM Gas Tankless Water Heaters
• Water Heaters with UEF 4.0 or Higher
• 120-Volt (Plug-In) Heat Pump Water Heaters
• 240-Volt Heat Pump Water Heaters
• Split-System Heat Pump Water Heaters
• Smart (Connected) Water Heaters
• Propane Water Heaters

Best water heater for your household

Sized from your peak hour — first-hour rating and winter flow-rate math, not tank stickers.

• a Family of 2
• a Family of 3
• a Family of 4 (2 bathrooms)
• a Family of 5
• a Family of 6 or More
• a 1-Bathroom Home
• a 2-Bathroom Home
• a 3-Bathroom Home
• a Small Apartment or Condo
• a Large Family Home (4+ bathrooms)

Popular water heaters

• A. O. Smith ACTH-199M-(N,P) 1
• A. O. Smith ATHR-160M 1
• A. O. Smith ATHR-160M 1 (ATHR-160X3 1)
• A. O. Smith GC6-PS4050-V 1 40-Gallon
• A. O. Smith GC6-PS5065-V 1 50-Gallon
• A. O. Smith GPCC-40L 1 40-Gallon
• A. O. Smith Heat Pump 80-Gallon (HPA10-80H45DV 2)
• A. O. Smith Heat Pump 80-Gallon (HPS10-80H45DV 2)
• A. O. Smith Heat Pump 80-Gallon (HPSN10-80H45DV 2)
• American ATHR-160M 1 (MTHR-160M 1)
• American ATHR-160M 1 (MTHR-160X3 1)
• American ATHR-180M 1 (MTHR-180M 1)

Buying and installation guides

• Heat pump vs gas water heater: the running-cost math
• Tank vs tankless water heater: which fits how you use hot water?
• How to size a water heater by household (first-hour rating and GPM)
• 40 vs 50 gallon water heater: when the smaller tank is enough
• Tankless water heater sizing: real GPM at your groundwater temperature
• 120 V vs 240 V heat pump water heaters: plug-in convenience vs recovery speed
• UEF explained: what the efficiency number actually means in dollars
• What a water heater really costs to run per year
• Heat pump water heater installation requirements (space, air, drain, noise)
• Gas water heater venting: atmospheric, power vent, and direct vent explained

New to water heaters? Start with the glossary — UEF, first-hour rating, and temperature rise in plain English.