About the Car CO2 Emissions Calculator
This car CO2 emissions calculator estimates the carbon dioxide your vehicle produces for any distance — a single trip, a commute or a full year of driving. Choose US units (miles and MPG) or metric (kilometres and litres per 100 km), pick gasoline, diesel or electric, and enter how far you drive and how efficient the car is. It returns total CO2 in kilograms, tonnes and pounds, grams per mile and per kilometre, and the fuel or electricity used.
Use it to compare two cars before you buy, to see what switching to an EV or a more efficient model would save, to report business travel emissions, or to size a carbon offset. The chart compares your result with the EPA’s typical passenger vehicle, which emits about 400 grams of CO2 per mile.
Tailpipe factors come from the US EPA: 8,887 g of CO2 per gallon of gasoline and 10,180 g per gallon of diesel. For electric cars the emissions depend on how your electricity is generated, so enter your grid’s carbon intensity; the default of 0.37 kg per kWh is close to the US average. The figures cover CO2 from fuel use only, not manufacturing, fuel production or other greenhouse gases.
With the default inputs, the co2 emitted is 4,603.6 kg. Change any value above to recalculate instantly.
How to use the car co2 emissions calculator
- 1Choose US or metric units and your fuel type.
- 2Enter the distance — one trip or a whole year.
- 3Enter your fuel economy (MPG or L/100 km), or kWh per 100 miles/km for an EV.
- 4For an EV, set the carbon intensity of your electricity.
- 5Read total CO2 and the per-mile and per-km figures.
Formula and method
For a combustion car the fuel used is distance ÷ MPG (US) or distance × L/100 km ÷ 100 (metric, converted at 3.785 L per US gallon). Almost all the carbon in the fuel leaves the tailpipe as CO2, so multiplying gallons by the EPA factor gives the emissions: 8,887 g per gallon of gasoline (about 2.35 kg per litre) and 10,180 g per gallon of diesel (about 2.69 kg per litre).
For an electric car, electricity used is distance × efficiency (kWh per 100 miles or km) ÷ 100, multiplied by the carbon intensity of the grid that charges it. Per-mile and per-km figures divide the total by the distance. The comparison uses the EPA’s typical passenger vehicle at about 400 g CO2 per mile.
- 8.887
- kg CO2 per US gallon of gasoline (EPA)
- 10.180
- kg CO2 per US gallon of diesel (EPA)
- grid
- kg CO2 emitted per kWh of electricity generated
Worked examples
Typical US car for a year
Driving 11,500 miles at 22.2 MPG burns about 518 gallons of gasoline. At 8,887 g per gallon that is roughly 4,604 kg — about 4.6 metric tons, matching the EPA’s figure for a typical passenger vehicle.
Diesel hatchback, 15,000 km a year
15,000 km at 5.5 L/100 km uses 825 litres (about 218 US gallons) of diesel. At 10,180 g per gallon that is about 2,219 kg of CO2, or 148 g per kilometre.
Electric car on an average US grid
12,000 miles at 30 kWh per 100 miles uses 3,600 kWh. At 0.37 kg CO2 per kWh that is 1,332 kg a year — 111 g per mile, under a third of a typical gasoline car.
Frequently asked questions
How much CO2 does a car emit per mile?+
The EPA puts a typical US passenger vehicle at about 400 g of CO2 per mile, based on 22.2 MPG. A 40 MPG car emits about 222 g per mile and a 15 MPG truck about 592 g per mile.
How much CO2 comes from a gallon of gasoline?+
Burning one US gallon of gasoline produces about 8,887 g (roughly 19.6 lb) of CO2, and a gallon of diesel about 10,180 g. The CO2 weighs more than the fuel because each carbon atom combines with two oxygen atoms from the air.
Do electric cars produce CO2?+
They have no tailpipe emissions, but the power plants that generate their electricity may. On a grid averaging 0.37 kg CO2 per kWh, an EV using 30 kWh per 100 miles is responsible for about 111 g per mile; on a low-carbon grid it can be far less.
How do I convert MPG to g CO2 per km?+
Divide 8,887 by your MPG to get grams per mile for gasoline, then divide by 1.609 to get grams per kilometre. For example 30 MPG gives about 296 g per mile, or 184 g per km.
Does this include other greenhouse gases?+
No. It covers CO2 from burning fuel or generating electricity. Methane and nitrous oxide from the tailpipe and refrigerant leaks typically add only a few percent, while manufacturing and fuel production are separate life-cycle emissions.