Commercial Water Heater Size Calculator


Selecting the right-sized water heater is crucial for maintaining a consistent and reliable hot water supply in commercial settings. The Commercial Water Heater Size Calculator is a valuable tool that simplifies the process of determining the appropriate water heater size based on flow rate and temperature rise.


The calculator employs a straightforward formula to calculate water heater size:

Water Heater Size (GPM) = Flow Rate (GPM) * Temperature Rise (°F) / 8.33

How to Use

  1. Input the flow rate of water in gallons per minute (GPM).
  2. Specify the desired temperature rise in degrees Fahrenheit (°F).
  3. Click the “Calculate” button.
  4. The result will display the recommended water heater size in gallons per minute.


For instance, if your facility requires a hot water flow rate of 10 GPM and a temperature rise of 30°F, input these values into the calculator, click “Calculate,” and the result will indicate the optimal water heater size in GPM.


  1. Q: Why is it important to calculate water heater size accurately?
    • A: Accurate sizing ensures that the water heater can meet the hot water demands of a facility efficiently.
  2. Q: Can the calculator be used for residential water heater sizing?
    • A: While designed for commercial use, the calculator can provide insights for residential applications with accurate input values.
  3. Q: What is the significance of flow rate in water heater sizing?
    • A: Flow rate represents the volume of hot water needed, a crucial factor in determining the appropriate water heater size.


The Commercial Water Heater Size Calculator is an essential tool for businesses seeking to optimize their hot water systems. Use this calculator to ensure your commercial space is equipped with a water heater that meets its specific demands, providing comfort and efficiency.

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