Water Heater Size Calculator
Who it's for: Plumbing contractors, service technicians, estimators, and homeowners.
Calculator Inputs
Quick Summary
- Built for: Plumbing contractors, service technicians, estimators, and homeowners.
- Key outputs: Recommended tank gallon range, Suggested common tank size, and more.
- Use this page for early planning estimates before final code and manufacturer verification.
Inputs
- Occupant count
- Bathroom count
- Simultaneous shower count
- Peak-use profile
Outputs
- Recommended tank gallon range
- Suggested common tank size
- Peak-demand note
How this calculator estimates results
- Builds a demand estimate from occupants, bathrooms, and simultaneous shower assumptions.
- Applies peak-use profile multipliers to account for low, average, or high demand behavior.
- Maps estimated demand to common storage tank sizes and a practical range for planning discussions.
Cross-check assumptions with Expansion Tank Size Calculator for a more complete planning workflow.
Common ranges and tips
- Use realistic simultaneous-use assumptions, especially for morning peak periods.
- Check fixture flow rates and usage habits before finalizing equipment size.
- Cross-check with the Fixture Flow Rate Calculator for demand context.
- Confirm final sizing with manufacturer first-hour ratings and local requirements.
Related Calculators
FAQ
No. Tank volume and first-hour recovery are related but different; review both when selecting final equipment.
Not directly. It provides a storage-tank estimate and should be supplemented with flow-temperature-rise calculations for tankless units.
Bathroom count helps approximate potential simultaneous demand, which can change practical sizing even at similar occupancy levels.
Disclaimer: Use results for planning only. Final design and installation decisions must follow local code and manufacturer documentation.
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