Hot Water Heater Size Calculator

Water Heater Size Formula:

\[ Size = (showers \times 20) + other \]

Water Heater Size (gallons):

Definition: This calculator estimates the required size (in gallons) of a water heater based on household shower count and other hot water usage.

Purpose: It helps homeowners and plumbers determine the appropriate water heater capacity for a home's needs.

The calculator uses the formula:

\[ Size = (showers \times 20) + other \]

Where:

Explanation: Each shower is estimated to require 20 gallons of hot water capacity, plus any additional hot water needs.

Details: Correct sizing ensures adequate hot water supply while avoiding energy waste from an oversized unit.

Tips: Enter the number of showers in your home and estimate other hot water needs (dishwasher, laundry, etc.). All values must be ≥ 0.

Q1: Why 20 gallons per shower?
A: This accounts for typical shower duration and flow rate, plus recovery time between showers.

Q2: What counts as "other" usage?
A: Include dishwasher (5-10 gal), washing machine (15-20 gal), sinks (2-5 gal each), etc.

Q3: Should I round up the calculated size?
A: Yes, most experts recommend rounding up to the nearest standard tank size (40, 50, 75 gal, etc.).

Q4: Does this work for tankless water heaters?
A: No, tankless systems are sized by flow rate (GPM) rather than tank capacity.

Q5: What if I have a large soaking tub?
A: Add the tub capacity (typically 50-80 gallons) to your "other" usage.