Car Emissions Calculator Formula

Understand the math behind the car emissions calculator. Each variable explained with a worked example.

Use the Car Emissions Calculator

Formulas Used

Annual CO2 Emissions

co2_metric_tons = total_lbs / 2204.6

Annual CO2 (lbs)

co2_lbs = total_lbs

Gallons of Fuel Used

gallons_per_year = gallons_used

Variables

VariableDescriptionDefault
annual_milesAnnual Miles Driven(miles)12000
mpgFuel Economy(mpg)28
fuel_co2_per_gallonCO2 per Gallon of Fuel(lbs)19.6
gallons_usedDerived value= annual_miles / mpgcalculated
total_lbsDerived value= gallons_used * fuel_co2_per_galloncalculated

How It Works

How to Calculate Car CO2 Emissions

Vehicle emissions depend on how far you drive and how efficient your car is.

Formula

CO2 (lbs) = (Annual Miles / MPG) * CO2 per Gallon

  • Gasoline produces about 19.6 lbs CO2 per gallon
  • Diesel produces about 22.4 lbs CO2 per gallon

    • Divide pounds by 2,204.6 to get metric tons.

    Worked Example

    You drive 12,000 miles per year in a car that gets 28 mpg.

    annual_miles = 12000mpg = 28fuel_co2_per_gallon = 19.6
    1. 01Gallons used: 12,000 / 28 = 428.6 gallons
    2. 02CO2 in lbs: 428.6 * 19.6 = 8,400 lbs
    3. 03CO2 in metric tons: 8,400 / 2,204.6 = 3.81 metric tons

    Frequently Asked Questions

    How much CO2 does a typical car produce?

    A car driven 12,000 miles at 25 mpg produces about 4.27 metric tons of CO2 per year.

    Does diesel produce more CO2 than gasoline?

    Yes, diesel produces about 22.4 lbs of CO2 per gallon compared to 19.6 for gasoline, but diesel engines are often more fuel-efficient.

    How do electric cars compare?

    EVs produce zero tailpipe emissions. Including electricity generation, an EV typically produces 50-70% less CO2 than a comparable gasoline car.

    Ready to run the numbers?

    Open Car Emissions Calculator