Carbon emissions in logistics are calculated by multiplying the fuel or energy consumption of each transport leg by an emission factor. If no fuel data is available, the product of tonnes carried and kilometres (tonne-km) and default emission intensities are used. The international reference is the ISO 14083 standard; the GLEC Framework puts this method into practice and calculates on a well-to-wheel (WTW) basis.
Which standards and frameworks are used?
- ISO 14083: Published in 2023, this standard defines a common method for quantifying and reporting greenhouse gas emissions arising from transport chain operations. In Europe it has been adopted as EN ISO 14083:2023. It is not a management system standard; it sets rules for calculation and reporting.
- GLEC Framework: An implementation guide published by Smart Freight Centre and kept consistent with ISO 14083. It provides default emission intensities by mode and a data hierarchy.
- GHG Protocol Scope 3: Cargo owners usually report transport emissions under the upstream and downstream transportation categories.
- EU CountEmissionsEU: According to the European Commission, the regulation that took effect on 1 June 2026 adopts EN ISO 14083:2023 as the reference method. It applies to companies that disclose their emissions voluntarily; full implementation is expected to be completed by the end of 2030.
The basic calculation logic
The most accurate method is based on primary data: emissions = fuel or energy consumed × emission factor. If this data is not available, the activity-based method is used: emissions = tonnes carried × distance (km) × emission intensity (g CO2e/tonne-km). For example, carrying 20 tonnes of cargo over 1,000 km amounts to 20,000 tonne-km; this value is multiplied by the intensity appropriate to the vehicle type.
| Concept | Emissions covered |
|---|---|
| WTT (well-to-tank) | Extraction, refining and transport of the fuel, or generation of electricity |
| TTW (tank-to-wheel) | Combustion of the fuel in the vehicle |
| WTW (well-to-wheel) | The sum of WTT and TTW; the boundary on which ISO 14083 is based |
A calculation reporting only TTW can show zero emissions for electric vehicles and trains; WTW also takes into account the emissions from electricity generation.
Step-by-step calculation
- Break the chain down into legs: for example, road from the factory to the port, port handling, the sea leg and road at destination.
- Collect the data for each leg: mode, vehicle or vessel type, fuel type, load factor and empty running.
- Choose the data type: primary fuel data first, otherwise the carrier's modelled data, and default values as a last resort.
- Add the transhipment points: energy consumption at terminals, warehouses and transhipment hubs is also part of the transport chain.
- Allocate to the shipment: in a shared vehicle, total emissions are usually allocated to shipments in proportion to tonne-km.
- Report transparently: the method used, data types, assumptions and sources of factors are stated in the report.
The general picture across modes
Emission intensity per tonne-km is generally highest for air freight and lowest for sea and rail freight; road lies in between. For a single trip, however, the ranking can change. A half-empty truck produces far more emissions per tonne-km than a full one. In rail, the result depends on whether the line is electrified and on the source of grid electricity. The cost and time aspects of mode choice are discussed in the entries air freight or sea freight and rail freight transport; for planning that reduces distance and empty running, see the entry on route optimisation.
CBAM and customer reporting requests
According to the European Commission, the EU Carbon Border Adjustment Mechanism (CBAM) applies in its definitive regime from 1 January 2026 and covers cement, iron and steel, aluminium, fertilisers, electricity and hydrogen. CBAM focuses on the emissions embedded in the production of goods; transport emissions are not the main subject of this declaration. Nevertheless, EU buyers may request shipment-level emissions data from their suppliers and logistics providers for their own Scope 3 reports. In international road transport, such requests are usually met by sharing route, distance, vehicle type and cargo weight data per trip.
Common mistakes
- Using straight-line distance; the actual route distance should be used.
- Ignoring empty running and load factor.
- Mixing different methods for different legs without stating this in the report.
- Presenting a calculation made under ISO 14083 as a "certificate"; the standard defines a method and does not certify the organisation. An environmental management system certificate under ISO 14001 is a separate matter.