Bath vs Shower Calculator
Compare the weekly water footprint of a shower and a bath so you can see which habit is easier on your bill and the planet.
This version follows the Omni reference logic with shower flow, bath fill level, body displacement, and weekly frequency.
Water Use Summary
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Run the calculation to compare shower and bath water use.
Quick Answer
This calculator compares shower and bath water use using your own flow rates, duration, fill level, and weekly frequency, then tells you which option is lighter on water use.
How to Calculate
- Enter your shower flow rate and duration.
- Set how often you shower each week.
- Enter the bath tub size, fill level, and body weight.
- Click Calculate to see the weekly comparison.
Formula
Shower water = flow rate × power factor × minutes × weekly frequency
Bath water = (tub capacity × fill level + body displacement + faucet flow × faucet minutes) × weekly frequency
Body displacement ≈ body weight / 8.35
Worked Examples
Example 1: A 10-minute, full-power shower at 2.5 gpm uses 25 gallons each time.
Example 2: A half-filled 60-gallon tub with a 150 lb body displaces about 17.96 gallons and uses about 47.96 gallons total.
Example 3: 7 showers per week at 25 gallons each equals 175 gallons per week.
How to Interpret the Result
| Outcome | Meaning |
|---|---|
| Shower uses less | Your shower habit is the lower-water option. |
| Bath uses less | Your bath setup is the lower-water option. |
| Difference is small | Small habit changes could flip the winner. |
Frequently Asked Questions
Related Calculators
References
- OmniCalculator reference page
- Body displacement uses the common 8.35 lb per gallon approximation from the reference logic.
- Last reviewed: March 2026.