Bath vs Shower Calculator

Compare water use between a bath and a shower.

Bath water volume (gal)

Shower minutes

Shower flow rate (gpm)

Shower water (gal) 16.8

Water saved by (gal) 18.2

Formula: shower water = minutes × gpm

Step-by-step with your numbers:

1. Values used:

2. Bath water volume = 35 gal

3. Shower minutes = 8

4. Shower flow rate = 2.1 gpm

6. Shower water = 16.8gal

7. Water saved by = 18.2gal

Did we solve your problem today?

Compare the water use of a shower vs filling a bathtub.

The math behind it

shower water = minutes × flow rate. A bath usually uses 30–50 gallons.

8-min shower at 2.1 gpm → 16.8 gal (vs 35 gal bath = saves 18 gal).

Which is greener?

A short shower almost always beats a bath for water savings.