Freight emissions in Scope 3: tonne-km, categories 4 and 9

Transport of goods appears twice in Scope 3: upstream in category 4 and downstream in category 9. Which one applies depends mainly on who pays. See the 15 Scope 3 categories for the full list.

Category 4 or category 9?

Category 4 covers "Third-party transportation and distribution services purchased by the reporting company in the reporting year", "including inbound logistics, outbound logistics (e.g., of sold products)", plus storage of purchased products in warehouses and distribution centres. The guidance is explicit that "Outbound logistics services purchased by the reporting company are categorized as upstream."

Category 9 covers transport and storage of products you sold, between your operations and the end consumer, "(if not paid for by the reporting company)".

The tonne-km formula

The distance-based method needs "the mass, distance, and mode of each shipment". For each transport leg:

emissions = mass of goods (tonnes) × distance (km) × emission factor (kg CO2e per tonne-km)

then add up the legs. One tonne carried one kilometre is one tonne-km. A shipment of 12 tonnes carried 300 km is 3,600 tonne-km.

How much the mode matters

DESNZ 2026 factors per tonne-km show a spread of more than 50 times between the cleanest and most carbon-intensive modes:

Two details often missed:

• Load matters. The same articulated lorry is 0.06054 kg CO2e per tonne-km fully laden and 0.09728 at 50% laden, because emissions are shared over less cargo. Use "average laden" unless you know the load factor.
• Refrigeration adds emissions. A refrigerated articulated lorry at average load is 0.09166, against 0.07926 for a non-refrigerated one.

Worked example

A company imports 20 tonnes of goods a year from Asia: 18,000 km by container ship, then 400 km by articulated lorry from the port.

If 1 tonne of urgent stock instead went by air over 9,000 km, that tonne alone would be 4,782 kg without radiative forcing, close to the whole year's sea and road freight.

Data to ask carriers for

• Weight per shipment (or per pallet, with an average pallet weight).
• Origin and destination, or distance per leg.
• Mode and vehicle type; for road, whether refrigerated.
• If available, the carrier's own emissions per shipment and the method used. Carrier data is usually better than average factors; record its source.

Spend-based as a fallback

If you only know what you paid for freight, a spend-based factor gives a rough estimate. Treat it as a screening figure and replace it with tonne-km data for your largest flows.