Bath vs Shower Calculator: Water, Cost, CO2 and Break-Even

Your details

Switch between gallons and litres. Costs stay in US dollars.
Check your showerhead packaging. Standard heads: 2.5 gpm; WaterSense: 2.0 gpm; older heads up to 3.5 gpm.
gpm
The US average is about 8 minutes (EPA). Generation Z averages 21 minutes.
min
per week
Standard tub holds 40-50 gal when full; most people fill it 60-80%, so 30-40 gal is realistic. Whirlpool/soaking tubs can hold 60-80 gal.
gal
Used to estimate how much water your body displaces when you get in. A 160 lb person displaces about 1.8 gallons. Leave at default if you do not need this detail.
lb
Set to 0 if you only shower. Annual cost comparison still runs for a single session.
per week
Check your water bill: divide the water charge by gallons used. US average is about $0.007/gal ($7 per 1,000 gal).
$/gal
Electric resistance heaters cost roughly $0.013 per gallon heated at $0.14/kWh. Gas at $1.20/therm costs about $0.006/gal. Select Custom to enter your own figure.
Annual saving: shower vs bathBath is cheaper
-$104.00

Positive means showering at your frequency is cheaper than bathing at your frequency.

Water per shower20gal
Water per bath40gal
Cost per shower$0.400
Cost per bath$0.800
Annual shower cost$145.60
Annual bath cost$41.60
Break-even shower duration16min
Body displacement19.46gal
CO2 per shower324g
CO2 per bath648g
Shower490.2
Bath730.9

Annual saving: shower vs bath: -$104.00

  • Water used (gal)
  • Cost per session
  • Annual cost
  • CO2 (g)

Your 8-min shower uses 20.0 gal, less than the 40.0-gal bath.

  • The break-even point is 16.0 minutes: keep your shower under that and you use less water than the bath.
  • At this duration and frequency, bathing is about $104.00 cheaper per year than showering.
  • Switching to a WaterSense showerhead (2.0 gpm) from a standard head (2.5 gpm) cuts shower water use by 20% and extends your break-even time by 4 extra minutes per 40-gallon bath.
  • CO2 from water heating: 324 g per shower vs 648 g per bath. A gas water heater emits roughly half that.

Next stepTo save more, shorten your shower or install a low-flow showerhead. Even 2 fewer minutes at 2.5 gpm saves 5 gallons per shower.

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