Diet Carbon Footprint Calculator Formula

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

Use the Diet Carbon Footprint Calculator

Formulas Used

Annual Diet CO2

total_diet_co2 = beef_co2 + poultry_co2 + dairy_co2 + plant_co2

Beef CO2

beef_share = beef_co2

Poultry CO2

poultry_share = poultry_co2

Dairy & Plant CO2

dairy_plant = dairy_co2 + plant_co2

Variables

VariableDescriptionDefault
beef_lbsWeekly Beef(lbs)2
poultry_lbsWeekly Poultry(lbs)2
dairy_lbsWeekly Dairy(lbs)5
grains_veg_lbsWeekly Grains & Vegetables(lbs)10
beef_co2Derived value= beef_lbs * 52 * 27 / 2204.6calculated
poultry_co2Derived value= poultry_lbs * 52 * 6.9 / 2204.6calculated
dairy_co2Derived value= dairy_lbs * 52 * 3.2 / 2204.6calculated
plant_co2Derived value= grains_veg_lbs * 52 * 2.0 / 2204.6calculated

How It Works

How to Calculate Your Diet's Carbon Footprint

Food production is a major source of greenhouse gas emissions, varying widely by food type.

Emission Factors (lbs CO2 per lb of food)

  • Beef: ~27 lbs CO2/lb
  • Poultry: ~6.9 lbs CO2/lb
  • Dairy: ~3.2 lbs CO2/lb
  • Grains & Vegetables: ~2.0 lbs CO2/lb

    • Formula

    Annual CO2 = Sum of (Weekly lbs * 52 * Emission Factor) / 2,204.6

    Worked Example

    A person eats 2 lbs beef, 2 lbs poultry, 5 lbs dairy, and 10 lbs grains/veg per week.

    beef_lbs = 2poultry_lbs = 2dairy_lbs = 5grains_veg_lbs = 10
    1. 01Beef: 2 * 52 * 27 / 2,204.6 = 1.27 metric tons
    2. 02Poultry: 2 * 52 * 6.9 / 2,204.6 = 0.33 metric tons
    3. 03Dairy: 5 * 52 * 3.2 / 2,204.6 = 0.38 metric tons
    4. 04Plants: 10 * 52 * 2.0 / 2,204.6 = 0.47 metric tons
    5. 05Total: 1.27 + 0.33 + 0.38 + 0.47 = 2.45 metric tons/year

    Frequently Asked Questions

    Why does beef have such high emissions?

    Cattle produce methane during digestion and beef farming requires extensive land, water, and feed. Methane is about 28x more potent than CO2.

    How much can going vegetarian reduce emissions?

    Eliminating meat can reduce diet-related emissions by 50-70%. A vegan diet can cut dietary emissions by up to 75%.

    Are local foods better for emissions?

    Transportation accounts for only 5-10% of food emissions. What you eat matters more than where it comes from.

    Ready to run the numbers?

    Open Diet Carbon Footprint Calculator