What is a tonne-kilometre?

A tonne-kilometre is one tonne of cargo moved one kilometre. It is the standard freight activity unit because emissions scale with both how heavy a load is and how far it travels. Multiplying tonnes by kilometres gives the activity, which is then multiplied by an emission factor.

Where do the emission factors come from?

The defaults are representative well-to-wheel values aligned with the GLEC Framework and similar logistics inventories: road around 62, rail around 22, sea around 8, and air around 602 grams CO2e per tonne-km. Real factors vary by vehicle, fuel, and load factor, so the tool lets you override the figure.

Why is air freight so much worse than sea?

Air freight emits roughly seventy times more CO2e per tonne-km than sea freight because aircraft burn large amounts of fuel to stay aloft and carry comparatively little cargo. Shifting even part of a shipment from air to sea or rail is the single largest lever for cutting freight emissions.

How is the offset cost calculated?

The tool converts total emissions to tonnes of CO2e and multiplies by the carbon price you enter, in your currency per tonne. Voluntary offset prices commonly range from a few dollars to over fifty per tonne depending on project quality and permanence.

Is an offset the same as reducing emissions?

No. Offsets compensate for emissions you could not avoid by funding reductions elsewhere; they do not eliminate the original emissions. Best practice is to cut footprint first through mode shift, load consolidation, and routing, then offset the residual.

Freight Carbon Footprint & Offset Calculator

Every shipment has a carbon footprint that scales with how heavy it is and how far it travels. This calculator multiplies your freight activity in tonne- kilometres by a mode-specific emission factor to estimate CO2e, then prices an offset at your chosen carbon price for scope 3 logistics reporting.

How it works

The core formula is a single multiplication, repeated per leg:

activity (tonne-km) = weight (tonnes) x distance (km)
emissions (g CO2e)  = activity x emission factor (g CO2e per tonne-km)
emissions (t CO2e)  = emissions (g) / 1,000,000
offset cost         = emissions (t) x carbon price (per tonne)

The default emission factors are representative well-to-wheel values aligned with the GLEC Framework. Road is roughly 62, rail 22, sea 8, and air 602 grams CO2e per tonne-km. Because real intensity depends on vehicle type, fuel, and how full the vehicle runs, the factor is editable.

Example

A 10 tonne shipment moved 800 km by road is 8,000 tonne-km. At 62 g CO2e per tonne-km that is 496,000 g, or 0.496 t CO2e. At a 30 per tonne carbon price the offset costs about 14.88.

Notes

Mode shift dominates everything else: moving the same shipment by rail instead of road cuts emissions by roughly two-thirds, and switching air to sea cuts them by over ninety-five percent. Reduce first, then offset the residual.