The Freight Emissions Calculator estimates the greenhouse-gas emissions of moving goods, following the international standard ISO 14083:2023 and the GLEC Framework v3.2. Provide a shipment mass, a transport distance, and a mode — the API returns the CO2e for that leg, the exact emission factor used, and a citation of both the method and the source.
How it is calculated
emissions (kgCO2e) = mass (tonnes) × distance (km) × factor (kgCO2e/tonne-km)The emission-intensity factor depends on the mode (road, rail, sea, air, inland waterway) and sub-mode (e.g. articulated HGV, container ship, air freighter). You provide the distance — this tool does not route or geocode. The product of mass and distance is the transport activity in tonne-kilometres.
Well-to-wheel vs tank-to-wheel
WTW (well-to-wheel) counts both the upstream energy production and the vehicle's operation; TTW (tank-to-wheel) counts only combustion/operation. The calculator returns both where the source factor provides them, and lets you select which is the headline figure via the basis parameter (WTW by default).
Factor sources (open authorities)
Factors are sourced from three open, citable authorities — each verified against its primary publication and carried with per-factor provenance:
- UK DEFRA / DESNZ conversion factors — Open Government Licence v3.0 (TTW + WTW).
- US EPA GHG Emission Factors Hub — US Government work, public domain (TTW).
- ADEME Base Carbone — Licence Ouverte / Etalab (WTW, incl. upstream).
Pick the source with the region parameter (uk = DEFRA, us = EPA, fr = ADEME); each mode has a sensible default. The full method, factor table and assumptions are documented in our methodology.
Worked example
Moving 10 tonnes by road over 500 km (UK DEFRA, all-HGV average, WTW): 10 × 500 × 0.12715 = ≈ 635.75 kgCO2e well-to-wheel (TTW ≈ 517.8 kgCO2e). Switch mode, sub_mode, region or basis to compare.
Frequently asked questions
Does it calculate distance for me?
distance_km. Routing, real road/sea distances and transit times are carrier-commercial and out of scope — this tool multiplies your distance by a published factor.Is this an official carbon report?
Which modes are covered?
/api/emissionsBest-effort estimate per ISO 14083 / GLEC using published open factors — not a verified or audited carbon report, not legal advice, and not a regulatory determination. Verify against the current source before reporting.