Tankless Water Heater Calculator

Size your tankless unit by flow rate (GPM)
1Unit Type
Tankless Only Hot water only
Combi Unit Hot water + space heating
2People in Household
1-2 People
3-4 People
5+ People
3Number of Bathrooms
1 Bathroom
2 Bathrooms
3+ Bathrooms
4Max Simultaneous Fixtures
1 Fixture ~2 GPM
2 Fixtures ~4 GPM
3 Fixtures ~6 GPM
4+ Fixtures ~8+ GPM
5Fixture Types (Select All That Apply)
Shower 2.0 GPM each
Soaker Tub 4.0 GPM
Kitchen Faucet 1.5 GPM
Laundry 2.0 GPM
6Current Fuel Source
Natural Gas Most common
Liquid Propane LP / Bottled
Note: Tankless units can be converted between Natural Gas and Propane with a kit.
7Service Area
Arnprior
Ottawa
Perth
Smiths Falls
8Water Source
City Water A.O. Smith + Navien
Well Water A.O. Smith Only
9Space Heating Requirements
Up to 1500 sq ft
1500–2500 sq ft
2500+ sq ft