Making sense of mobility
What is the GB Rail Carbon Calculator?
The GB Rail Carbon Calculator is an API that estimates the carbon emissions for any passenger rail journey on the Great Britain rail network allowing businesses and passengers to quantify environmental impact with confidence.
​
Unlike generic emissions factors, this tool uses route-specific rail distances and offers two methodologies:​ It supports both UK Government standard emissions factors and a weighted model based on real train services. This makes it ideal for powering sustainability dashboards, supporting carbon reporting frameworks, and comparing rail against road or air for individual journeys.
​​
Built using trusted industry sources and regularly updated with GB rail data.
​
Use it to enrich sustainability dashboards, support carbon offsetting calculations, or improve public and internal reporting on transport emissions.​
An Standard Class Journey between Brockenhurst and Southampton Central emits:
-
1.47 kgCOâ‚‚ based on UK Government factors
-
0.67 kgCOâ‚‚ in our weighted model
Designed for Carbon Reporting and Regulation
Organisations are under increasing pressure to disclose carbon emissions accurately, not only to meet legal obligations but to maintain credibility with stakeholders, regulators, and investors.
​
The GB Rail Carbon Calculator supports this shift by offering route-specific, rail-only COâ‚‚ estimates based on the best available data, helping public and private sector organisations strengthen their environmental reporting.
​
It is especially relevant for:​
​
Scope 3 emissions disclosures: Including rail travel by staff, contractors, or customers — under frameworks like SECR (UK) and CSRD (EU)
​
Improving ESG and TCFD reporting: Where businesses are expected to use the most accurate data available, rather than default assumptions
​​​
Public sector compliance and accountability: Local authorities, transport bodies, and suppliers contributing to Net Zero goals can demonstrate rail-specific decarbonisation impact
​
​
Using the weighted emissions model (incorporating the Rail Delivery Group’s Green Travel Data), this API reflects actual train types, typical passenger loading, and fuel source, offering a significant step forward from averages or spreadsheets.​​​
The product helps ensure your carbon reporting keeps pace with evolving standards.
How it works
The Carbon Calculator measures the shortest route between two stations and applies emission factors to estimate CO₂ output per passenger.​
You can choose between:
-
Standard carbon factors from the UK Government
-
Weighted factors from the rail industry’s Green Travel Data - accounting for engine type, train configuration, and passenger loading​
​​​The result includes:
-
Route path
-
Distance in kilometres and miles
-
Emissions per average passenger, plus a granular calculation for a passenger travelling in Standard Class and 1st Class.​
Example: For a journey from Brockenhurst (BCU) to Southampton Central (SOU):
-
Distance: 21.87 km
-
COâ‚‚e emissions per passenger travelling in Standard Class =
-
UK Government figure: 1.47 kg​ / Weighted industry figure: 0.67 kg
-
Weighted emissions reflect real operational conditions — including engine type, carriage count, fuel source, and average passenger load. This produces a more accurate and defensible figure than static government averages.
Who it’s for
A versatile tool used across industries to align transport decisions with sustainability goals.
Mobility and journey apps to inform passengers about greener journey options in real time
Hospitality and tourism platforms to offer eco-friendly journey comparisons and offsetting tools
Retail and commercial businesses to analyse sustainability-driven footfall and campaign effectiveness​
Public sector authorities evaluating emissions by mode for transport strategy and Net Zero plans
Travel management companies to power COâ‚‚ dashboards and track staff emissions
AI assistants or agentic workflows that recommend low-carbon travel choices or explain emissions calculations
Urban planners and smart city developers to compare route-level carbon outputs and optimise modal shift
ESG teams looking to move beyond averages and report verified data across journeys
Government suppliers needing high-quality carbon estimates to support low-carbon tender scoring
Digital platforms integrating rail-specific carbon into multimodal journey planners
This API supports the principle of using best-available data where it exists and makes it easy to compare routes or publish evidence-based carbon metrics.
Try it or subscribe
Available to test or subscribe. Suitable for direct integration into ESG systems, public dashboards, or emissions reporting pipelines.
DataWharf feeds are available via the Rail Data Marketplace with subscription offers tailored to suit rail industry organisations as well as general users. Full details are available on each product listing via the links below. Contact us to discuss bespoke packages.
Explore more with DataWharf
The GB Rail Carbon Calculator works best when combined with other DataWharf APIs.
Popular combinations include:
Explore our suite of APIs or contact us to discuss a custom bundle for your use case.