Trip Carbon Footprint Calculator
Written by Thierno Sadou Diallo, formula verified per our methodology • Last checked on 9/3/2026
A trip's CO2 emissions mainly depend on the mode of transport: for the same distance, planes and private cars emit far more than trains — about 75 to 80 times more than a high-speed train, according to French agency ADEME. Example: 100 km by car emits about 21.8 kg of CO2e, versus 0.3 kg by high-speed train.
Explanation
This calculator uses average per-passenger emission factors published by ADEME (France's environment and energy agency, Base Empreinte): each mode of transport is assigned a number of grams of CO2 equivalent emitted per kilometer traveled and per passenger, including a share of vehicle manufacturing and maintenance amortized over its lifetime (except for cycling and walking, see the FAQ). These are national averages, not a measurement of your specific trip: an electric car, a carpool with 4 people, or a plane at full capacity all have a very different per-passenger impact than a solo trip in a large sedan. The result is therefore a useful order of magnitude for comparing modes of transport, not a certified individual carbon footprint. With the factors used here, a high-speed train trip emits about 75 times less CO2 than a private car and about 78 times less than a plane, for the same distance — the gap is smaller against a regional train, whose emission factor is higher (a regional train still emits about 8 times less than a car).
Example: 100 km by car
Inputs
Distance: 100 km. Mode: gasoline car.
Calculation
The average emission factor used for a gasoline car is 218 g CO2e per km per passenger. Over 100 km: 100 × 218 = 21,800 g, or 21.8 kg of CO2e.
Result
This 100 km car trip emits about 21.8 kg of CO2e.
Frequently asked questions
Are these figures accurate for a specific trip?
No, these are national per-passenger averages. An electric car, a different occupancy rate (carpooling), or a particular vehicle model significantly change the real result. This calculator gives an order of magnitude for comparing modes of transport, not a certified measurement of your trip.
Why does the train emit so much less than a car?
Mainly because a train carries hundreds of passengers at once for a much lower energy consumption per passenger, and because the electricity powering the French rail network is very largely decarbonized (nuclear and renewables).
Why are cycling and walking counted as zero emissions?
Because this calculator doesn't count the manufacturing of the bicycle or the food intake of the walker, which are outside the scope chosen here. This is a difference in treatment worth knowing: the other modes in this calculator do include a share of vehicle manufacturing and maintenance (about a fifth of the total for a high-speed train, for example), amortized over its lifetime. Cycling does have a real manufacturing impact, but it remains far lower than a car's or a train's per kilometer, and was left out for simplicity.