Bath Vs Shower Footprint Calculator

gal
Typical bath uses 25–45 gallons.
min
gal/min
Low-flow: 1.5 gpm; Standard: 2.1 gpm; Power: 2.5+ gpm.
Everyday Life

Compare the water usage and CO₂ footprint of taking a bath versus a shower.

Formula

Shower water = duration × flow rate; CO₂ = gallons × emission factor
  • Gas water heating: ~0.1 kg CO₂ per gallon heated.
  • Electric (grid avg): ~0.231 kg CO₂ per gallon heated.
  • Typical bath: 35 gallons. Typical 8-min shower: ~17 gallons.

8-minute shower vs 35-gallon bath (gas heat)

Inputs
  • Bath Water Volume: 35 gal
  • Shower Duration: 8 min
  • Shower Flow Rate: 2.1 gal/min
  • Water Heating: gas

Shower = 8×2.1 = 16.8 gal (1.68 kg CO₂). Bath = 35 gal (3.5 kg CO₂). Shower wins.

Frequently asked questions

Is a shower always better?
Usually yes, but a long shower (>17 min at 2.1 gpm) uses more water than a bath.
What is a low-flow showerhead?
Low-flow showerheads use 1.5 gpm or less vs the standard 2.1 gpm.
How is CO₂ calculated?
Based on energy needed to heat the water and emission factor of the fuel type.
What is the break-even shower length?
At 2.1 gpm vs 35-gallon bath, the break-even is about 16.7 minutes.