Freight Emissions Calculator

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

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.

What the result tells you

• Use actual gross mass — the physical weight of the goods, not chargeable or volumetric weight. Entering chargeable weight (a habit for air shipments) overstates the result; the response confirms mass_basis: "actual_gross_mass".
• Empty running is already in the factor. These are fleet/sector-average factors — for DEFRA, US EPA, and ADEME road & sea they already include average empty running and load (empty_running: "sector_average_included"), so don't add your own empty-return leg. Where the source doesn't state it (ADEME air / inland waterway) the field is "see_source".
• Sea & air are low-representativeness defaults. The response carries representativeness: "low" and a high-variance note in the summary: actual sea/air emissions vary materially by vessel/aircraft type, load factor and routing — treat these as screening estimates, not reporting figures (road and rail are "medium"). On this page the sea/air figure is rounded (~) to signal that; the API keeps full precision.
• Every factor is dated. _source.factor.last_verified is the date the value was last verified against its published source.

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

Best-effort estimate computed using the ISO 14083 / GLEC distance-based method with published open factors — not a verified or audited carbon report, not legal advice, and not a regulatory determination. Use actual gross mass (not chargeable/volumetric); sea/air are low-representativeness generic defaults. Verify against the current source before reporting.