The Carbon Emission of a UK Train Journey

Written by Kit Brennan on 7 Jan 2021

In the UK, a train journey still has the lowest carbon emissions of any transport method in the country. Calculating the emissions of one is surprisingly simple thanks to the conversion factors provided by the UK Government.

To calculate the carbon emissions of a UK train journey, first, you need to find the route distance in question. As trains, like aeroplanes, don't travel in a straight line from A to B, it is important to find the actual rail distance. This may be provided by your travel provider, but if not, you can check manually on websites like this one. Once you have the distance, you simply need to multiply the distance in kilometres (km) by the conversion factors displayed below.

Type CO2e per pkm CO2 per pkm CH4 per pkm N2O per pkm
National rail

0.03694kg

0.03659kg

0.00006kg 0.00029kg
International rail

0.00497kg

0.00492kg

0.00002kg 0.00003kg
Light rail & tram 0.02991kg 0.02964kg 0.00009kg 0.00018kg
London Underground 0.0275kg 0.02726kg 0.00008kg 0.00016kg

Note: Units are in per passenger-kilometre (pkm). For example, 2 people travelling 100km would be 200 passenger-kilometres.

As you can see, the factors differ depending on whether you travel nationally, internationally, or on the Underground! They are also dependant on the type of greenhouse gas. Best-practice is to calculate CO2e, as it best represents total emissions.

Worked example: 2 people travel 100 miles by train. 100 miles is 161 kilometres. Since we measure in passenger-kilometres, we need to multiply the kilometres by the number of passengers, to get 322 passenger-kilometres. Finally, we multiply this by the number in the table (0.0394) to get 11.9 kg of CO2e.

Here are some carbon emissions calculations on some popular UK routes:

  • The carbon emissions of London Paddington to Birmingham New Street by train is 6.61 kg of CO2e (179 km travelled per passenger).
  • The carbon emissions of London Paddington to Edinburgh by train is 24.90 kg of CO2e (647 km travelled per passenger).
  • The carbon emissions of London Paddington to Manchester Piccadilly by train is 11.41 kg of CO2e (309 km travelled per passenger).
  • The carbon emissions of Birmingham New Street to Manchester Piccadilly by train is 4.95 kg of CO2e (134 km travelled per passenger).

To power this article and our calculation, we have relied upon expert research by the UK Government's Department for Business, Energy & Industrial Strategy, and the Department for Environment, Food & Rural Affairs. The distances have been sourced from RailMiles.

You can find more conversion factors here. For detailed explanations, stay tuned for more data-driven insights from the Thrust Carbon team. Let’s make travel effortlessly green together.

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