How we calculate carbon footprint for each rail journey
The greenhouse gas emission figures we provide to passengers for each journey are calculated using a precise, regulated methodology. Learn more.
For over a decade, France’s Grenelle II environmental law has required transport providers to disclose the amount of CO2 emitted for each journey. This requirement has a dual purpose: make transport players aware of their carbon impact, and encourage travellers to choose cleaner mobility options.
How we comply
We report emissions for each journey—expressed in CO2 equivalent (CO2e)—whenever a customer searches for a journey. We updated these values in August 2025 based on the input database for 2024.
General methodology
DOCUMENT
Our methodology complies with French law and guidelines published by the French State. It’s based on the draft European standard for calculating and reporting energy consumption and GHG emissions from transport1.
EnglishPDF • 4.2MB
Download General methodology - English - pdf - 4.2MBGreenhouse gas emissions from transport in France
Did you know? In France, transport (of people and goods) is the main source of greenhouse gas emissions (GHG), accounting for 34% of national GHG emissions (including metropolitan France and overseas territories) in 2023. More than half of the GHG actually come from the use of private cars2. By way of comparison, road transport as a whole accounts for almost all emissions from the transport sector, while emissions from rail transport account for less than 1%.
Doing the maths
To calculate the carbon footprint for a journey, we multiply the distance travelled by the average amount of CO2e emitted per passenger per kilometre, based on the type of train—TGV INOUI, OUIGO, INTERCITÉS, TER or Transilien.
For example, if a passenger travels from Strasbourg to Versailles on a TGV and a Transilien commuter train, the formula is:
Distance travelled with TGV INOUI x GHG emissions per kilometre for a TGV INOUI passenger + Distance travelled with Transilien x GHG emissions per kilometre for a Transilien
Zeroing in on the numbers
Averages updated annually
We take the distance from a database of railway lines in kilometres. For each type of train, we calculate average annual emissions by multiplying energy consumption for the preceding year by the CO2e emission factor for each type of energy, and dividing the result by the number of passengers carried that year and the distance they travelled.
The whole story
This method covers only the “energy use” portion of our CO2e footprint--the carbon impact of the traction energy consumed by the train. To provide comprehensive emissions data for SNCF mobility solutions, we took part in a working group led by Ademe, France’s Agency for Ecological Transition, on the impact of manufacturing our vehicles. We also joined a study by the consulting firm Carbone 4 on including the carbon impact of both manufacturing and maintenance, plus consumption by our maintenance centres.