Carbon Footprint Calculator Formula

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

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Formulas Used

Total Annual CO2

total_co2_lbs = driving_co2 + electric_co2 + gas_co2 + flight_co2

In Metric Tons

total_co2_tons = (driving_co2 + electric_co2 + gas_co2 + flight_co2) / 2204.6

Driving CO2

driving_share = driving_co2

Home Energy CO2

home_share = electric_co2 + gas_co2

Variables

VariableDescriptionDefault
miles_drivenAnnual Miles Driven(miles)12000
vehicle_mpgVehicle MPG(MPG)28
electricity_kwhMonthly Home Electricity(kWh)900
gas_thermsMonthly Natural Gas(therms)40
flight_hoursAnnual Flight Hours(hrs)10
driving_co2Derived value= miles_driven / vehicle_mpg * 19.6calculated
electric_co2Derived value= electricity_kwh * 12 * 0.92calculated
gas_co2Derived value= gas_therms * 12 * 11.7calculated
flight_co2Derived value= flight_hours * 90 * 2.2calculated

How It Works

How Carbon Footprint Is Estimated

Your carbon footprint includes emissions from transportation, home energy, and air travel.

Emission Factors Used

  • Driving: 19.6 lbs CO2 per gallon of gasoline
  • Electricity: 0.92 lbs CO2 per kWh (US average)
  • Natural Gas: 11.7 lbs CO2 per therm
  • Flights: ~90 kg CO2 per flight hour per passenger (x 2.2 for lbs)

    • Worked Example

    12,000 miles at 28 MPG, 900 kWh/mo electricity, 40 therms/mo gas, 10 flight hours.

    miles_driven = 12000vehicle_mpg = 28electricity_kwh = 900gas_therms = 40flight_hours = 10
    1. 01Driving = 12,000 / 28 x 19.6 = 8,400 lbs CO2
    2. 02Electricity = 900 x 12 x 0.92 = 9,936 lbs CO2
    3. 03Natural gas = 40 x 12 x 11.7 = 5,616 lbs CO2
    4. 04Flights = 10 x 90 x 2.2 = 1,980 lbs CO2
    5. 05Total = 8,400 + 9,936 + 5,616 + 1,980 = 25,932 lbs = 11.8 tonnes

    Ready to run the numbers?

    Open Carbon Footprint Calculator