Household Inputs

Household Size
Daily Hot Water Use
Appliances
Additional Use (Optional)
Advanced Settings

Tweak the settings below if you know the flow rate for your individual appliances or just want to get a clearer idea of how use changes throughout the year.

Your Results

This estimate is based on the information you entered.

Weekly Usage
N/A
Monthly Usage
N/A
Yearly Usage
N/A
Recommended Capacity
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For recommended products, see our Ultimate Guide to Tankless Water Heaters .
Where Did We Get These Numbers?

This tool uses figures pulled from real data and recommendations from a wide variety of official sources, including our own internal data. Click this box to learn how they’re implemented and get more helpful info for California residents.

  • Shower Flow: The combined total flow of all showerheads must not exceed 1.8 GPM (gallons per minute) as per CalGreen’s 2025 Residential Mandatory Measures .
  • Water Heater Temperature: The U.S. Department of Energy recommends setting your water heater to 120°F for general use.
  • Clothes Washer Water Use: According to ENERGY STAR, certified high-efficiency washers typically use about 14 gallons of water per load.
  • Dishwasher Water Use: Statistics published by KitchenAid show that modern dishwashers use somewhere between 3 and 4 gallons per cycle. For ease of use, this tool uses an average of 3.5 gallons.
  • Calculating How Hot Water Is Shared Between Appliances: All figures are based on average calculations outlined in the California Energy Commission's Water Heating Calculation Method .
  • Typical Per-Activity Water Use: Additional per-activity estimates (baths, brushing teeth, hand/face washing, shaving, and hand dishwashing) are based on data from the U.S. Geological Survey (USGS).
*Actual hot water use varies by fixture flow rates, appliance settings, and household routines.
For recommended products, see our Ultimate Guide to Tankless Water Heaters .
Where Did We Get These Numbers?

This tool uses figures pulled from real data and recommendations from a wide variety of official sources, including our own internal data. Click this box to learn how they’re implemented and get more helpful info for California residents.

  • Shower Flow: The combined total flow of all showerheads must not exceed 1.8 GPM (gallons per minute) as per CalGreen’s 2025 Residential Mandatory Measures .
  • Water Heater Temperature: The U.S. Department of Energy recommends setting your water heater to 120°F for general use.
  • Clothes Washer Water Use: According to ENERGY STAR, certified high-efficiency washers typically use about 14 gallons of water per load.
  • Dishwasher Water Use: Statistics published by KitchenAid show that modern dishwashers use somewhere between 3 and 4 gallons per cycle. For ease of use, this tool uses an average of 3.5 gallons.
  • Calculating How Hot Water Is Shared Between Appliances: All figures are based on average calculations outlined in the California Energy Commission's Water Heating Calculation Method .
  • Typical Per-Activity Water Use: Additional per-activity estimates (baths, brushing teeth, hand/face washing, shaving, and hand dishwashing) are based on data from the U.S. Geological Survey (USGS).
*Actual hot water use varies by fixture flow rates, appliance settings, and household routines.