​​Calculation methodology

The CO2 footprint of your trip is calculated as: the distance of your trip multiplied by the CO2 emissions of a passenger for the different means of transport, per kilometer. 
It concerns only the main part of the route and does not take into account the transport from / to the station or airport

Average emissions for a passenger per kilometer:

Trains Renfe-SNCF en Coopération
3,4 g of CO2 per kilometer

205 g of CO2per kilometer

168 g of CO2 per kilometer

Source Cars: Average use of particular cars France: Ministry of Sustainable Development and Energy - Observation and Statistics Service (SOeS), Cars’ average consumption in France and fuel emission factors: ADEME - Carbon Base​

Source Airplanes: Ministry of Sustainable Development and Energy "Information CO2 transport services - Methodological Guide" 2012 - For a 150-seat airplane performing a flight of less than 1000 km.