Freight CO₂e following the GLEC Framework and ISO 14083
Container shipping emissions are calculated the same way in the GLEC Framework v3.3 and ISO 14083: the cargo's tonnes, times the distance, times an emission intensity per tonne-kilometre. The work is in choosing the right distance and the right intensity.
Emissions (kg CO2e) = cargo (t) × distance (km) × intensity (g CO2e per tonne-km) ÷ 1,000
Report it well-to-wheel (WTW): the fuel burnt on the ship (tank-to-wheel, TTW) plus producing and delivering that fuel (well-to-tank, WTT). ISO 14083 asks for both.
Use the shortest feasible distance (SFD) between the two ports on the sea network, not a straight line: a straight line from Shanghai to Hamburg crosses Asia.
Ships sail further than the shortest route. The GLEC Framework (Section 1, Chapter 4, citing Clean Cargo) puts actual container distances at 15% above the shortest feasible route. GLEC's own container default values already include these 15%, so you use them with the SFD as it is. An intensity per tonne-km actually sailed needs the SFD × 1.15 first: the distance adjustment factor (DAF).
Pick an intensity for the trade lane. The lane matters: GLEC v3.3's container default values (Clean Cargo trade lane factors, reporting year 2025) go from 42.9 g CO2e per TEU-km for Asia to-from North Europe to 321.4 g within North America.
For Shanghai to Hamburg: Asia to-from North Europe, 35.3 g TTW + 7.6 g WTT = 42.9 g CO2e per TEU-km. Per tonne-km, with GLEC's average of 10 t per TEU: 3.53 g TTW + 0.76 g WTT = 4.29 g CO2e.
| Step | Value |
|---|---|
| Shortest feasible distance on the sea network | 20,018 km |
| Tonne-km: 10 t × 20,018 km (GLEC's value includes the 15%) | 200,180 tkm |
| Tank-to-wheel: 200,180 × 3.53 g | 707 kg CO2e |
| Well-to-tank: 200,180 × 0.76 g | 152 kg CO2e |
| Well-to-wheel | 859 kg CO2e |
Calculated live on Sootcase, October 2026. Open the calculator to redo it with your own shipment: every result shows these steps with their sources.
When you only know the number of containers, use the per TEU-km value directly, or the GLEC Framework's default cargo weights (Section 1, Chapter 2, p. 21): 10 t per TEU on average, 6 t for light and 14.5 t for heavy cargo. GLEC's own example (Section 3, Module 4): 10 TEU, Hamburg to Shanghai, 21,000 km × 42.9 g = 9.01 t CO2e.
In a 2024 study (Schramm & Lehner, IJPDLM 54(11)), six calculators gave 712 to 1,661 kg CO2e for this same 10 t Shanghai to Hamburg sea shipment. The difference comes from the distance (sea network or not, with or without the 15%) and the intensity (which ships, which year, WTW or TTW only). See the full comparison.