Green Airlines

Rankings / Routes / Flying vs driving

2025 figures

Flying vs driving vs train

Over 500 miles, a flight accounts for about 90 kg of CO2 per passenger and a car driven alone for about 174 kg. Put a second person in the car and it drops to 87 kg each. Over 1,500 miles the flight is 213 kg and the lone driver 521 kg. The number of people in the car decides the answer more than anything else.

A propeller plane approaching a runway in silhouette against the sun
Illustrative photo, not a specific airline's aircraft. Photo: w3design, DepositPhotos Standard licence, image 26006165.

Over 500 miles

CO2 per person over 500 milesBar chart of kilograms of CO2 per person over a 500 mile trip by flying, driving alone, driving with two or four people, bus and train.050100150Flight90 kgCar, alone174 kgCar, 2 people87 kgCar, 4 people43 kgBus39 kgTrain (other routes)87 kgTrain (Northeast)13 kg
CO2 per person over 500 milesBar chart of kilograms of CO2 per person over a 500 mile trip by flying, driving alone, driving with two or four people, bus and train.050100150Flight90 kgCar, alone174 kgCar, 2 people87 kgCar, 4 people43 kgBus39 kgTrain (other routes)87 kgTrain (Northeast)13 kg
CO2 per person over 500 miles, in kilograms. Less is better.

Over 1,500 miles

CO2 per person over 1500 milesBar chart of kilograms of CO2 per person over a 1500 mile trip by flying, driving alone, driving with two or four people, bus and train.0200400Flight213 kgCar, alone521 kgCar, 2 people261 kgCar, 4 people130 kgBus116 kgTrain (other routes)261 kgTrain (Northeast)40 kg
CO2 per person over 1500 milesBar chart of kilograms of CO2 per person over a 1500 mile trip by flying, driving alone, driving with two or four people, bus and train.0200400Flight213 kgCar, alone521 kgCar, 2 people261 kgCar, 4 people130 kgBus116 kgTrain (other routes)261 kgTrain (Northeast)40 kg
CO2 per person over 1,500 miles, in kilograms. Less is better.

How the choice changes with distance

A flight passenger's CO2 rises with distance more slowly than a driver's, because take-off and climb take a large share of the fuel on any flight and the rest of the trip is cheap per mile. A car emits at the same rate for every mile. That's why a person alone in a car is close to even with a short flight and well behind on a long one. A car with two people is lower than the flight from about 200 miles, and with four people it's lower everywhere.

CO2 per person by trip length, kilograms
Straight-line milesRoad milesFlightCar, aloneCar, 2 peopleCar, 4 peopleSUV, aloneBusTrainPeople in the car to match the flight
2002345369351792155 to 352
5005859017487432303913 to 872
1,0001,170151347174874617727 to 1743
1,5001,75521352126113069111640 to 2613
2,5002,9253368694342171,15219367 to 4363

Where each figure comes from

Sources: US Bureau of Transportation Statistics (BTS), T-100 traffic and Schedule T-2 fuel filings; US EPA GHG Emission Factors Hub. See the methodology.

  • Flight. The measured average for the 100 busiest US routes in 2025: for each airline and aircraft type we multiplied its air time by the gallons per airborne hour it reported to BTS, divided by the passengers carried. The trend line through those routes is about 28.6 kg plus 0.12 kg for every mile flown. It's a typical flight, not a particular airline: each route page has the airlines.
  • Car. The EPA figure for an average passenger car, 0.297 kg of CO2 per vehicle-mile, times road miles, divided by the people in the car. A pickup or large SUV is 0.394 kg per mile.
  • Road miles. 1.17 times the straight-line distance, the median of 30 of these city pairs measured on OpenStreetMap roads (range 1.07 to 1.32).
  • Bus and train. The EPA figures per passenger-mile: bus 0.066 kg, Amtrak on the Northeast Corridor 0.023 kg (mostly electric) and other Amtrak routes 0.149 kg. Rail distance is taken as about the road distance, and a direct train doesn't serve most city pairs.
  • What's left out. Only CO2 from burning fuel. Flights also warm the climate through contrails and nitrogen oxides, which this site doesn't count. Getting to the airport isn't counted, and neither is the time or cost of each choice.

See all 100 routes, how the airlines compare, or how a private jet compares with an airline seat.