Water Footprint Calculator Formula

Understand the math behind the water footprint calculator. Each variable explained with a worked example.

Use the Water Footprint Calculator

Formulas Used

Annual Water Footprint

total_footprint = direct_annual + meat_water + dairy_water + goods_water

Daily Water Footprint

daily_total = (direct_annual + meat_water + dairy_water + goods_water) / 365

Food Share

food_pct = (meat_water + dairy_water) / (direct_annual + meat_water + dairy_water + goods_water) * 100

Direct Use Share

direct_pct = direct_annual / (direct_annual + meat_water + dairy_water + goods_water) * 100

Variables

VariableDescriptionDefault
daily_direct_galDaily Direct Water Use(gallons)80
meat_servings_weekMeat Servings per Week7
dairy_servings_weekDairy Servings per Week10
monthly_goods_usdMonthly Consumer Goods Spending(USD)500
direct_annualDerived value= daily_direct_gal * 365calculated
meat_waterDerived value= meat_servings_week * 52 * 450calculated
dairy_waterDerived value= dairy_servings_week * 52 * 60calculated
goods_waterDerived value= monthly_goods_usd * 12 * 20calculated

How It Works

How to Calculate Your Water Footprint

Your water footprint includes direct use (showers, faucets) and virtual water embedded in food and products.

Virtual Water Examples

  • 1 lb beef: ~1,800 gallons
  • 1 serving meat: ~450 gallons
  • 1 serving dairy: ~60 gallons
  • $1 of consumer goods: ~20 gallons

    • Formula

    Total = Direct Use + Food Virtual Water + Goods Virtual Water

    The average American water footprint is about 2,000 gallons per day, with only 5% from direct use.

    Worked Example

    A person using 80 gal/day directly, eating 7 meat and 10 dairy servings/week, spending $500/month on goods.

    daily_direct_gal = 80meat_servings_week = 7dairy_servings_week = 10monthly_goods_usd = 500
    1. 01Direct: 80 * 365 = 29,200 gallons/year
    2. 02Meat: 7 * 52 * 450 = 163,800 gallons
    3. 03Dairy: 10 * 52 * 60 = 31,200 gallons
    4. 04Goods: 500 * 12 * 20 = 120,000 gallons
    5. 05Total: 29,200 + 163,800 + 31,200 + 120,000 = 344,200 gallons/year

    Ready to run the numbers?

    Open Water Footprint Calculator