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The Premier Online Plumbing Supplier Since 1995

Tankless Water Heater Sizing Guide
for residential applications

Feeling lost? Not sure how to decide amongst the choices here? Check out our tankless water heater buying guide for help figuring out what will best suit your needs
Step 1: Select the number and type of each fixture that your household typically uses simultaneously.
For example, someone showering while a load of laundry is being washed, or someone doing kitchen prep while the dishwasher is running, or two people showering in different bathrooms at the same time.
Showers (Average 2.5gpm flow rate)
Bathroom Faucets (Average 1.5gpm flow rate)
Kitchen Faucets (Average 2.2gpm flow rate)
Dishwasher (Average 2.0gpm flow rate)
Washing Machine (Average 1.5gpm flow rate)
Step 2: Find your location on the map and determine the average groundwater temperature for your area.
Note that this is only an average estimate and can vary with the season, weather, and other factors. Estimated temperature rise is calculated based on an assumed desired water temperature of 120°F overall.
Groundwater temperature:
Filter by Brand:
Estimated GPM Needed:
Your flow rate needs exceed capacity, we recommend using multiple heaters "ganged" together. Please revise your search to a lower flow rate and look for water heaters with this symbol, indicating the model can be "ganged".
Your flow rate needs are low enough to use a point-of-use heater, if desired. Browse our complete selection of point-of-use heaters to find models that install directly at the fixture.
Estimated Temperature Rise Needed: °F
Gas water heater - Gas heater
Electric water heater - Electric heater
Can be "ganged" for higher flow rate -
click any image to learn more and purchase that tankless water heater

Please note: This tool is intended only for use as a guide to the products we offer that meet certain criteria you may be looking for. The tankless water heaters shown here may or may not be suitable for your application, depending on other factors such as wiring/electrical needs, home plumbing configuration, water quality, and more. We strongly suggest you research the performance chart and detailed specifications (found on the product page for each model), then discuss the model you want with your plumber and/or electrician prior to purchasing.

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