Scope 3 Cat 4 Road Freight Calculator (GLEC + DEFRA)

What road freight covers in Scope 3 Category 4

GHG Protocol Scope 3 Category 4 — upstream transportation and distribution — covers the movement of purchased goods between a company’s tier-1 suppliers and its own operations, plus third-party logistics paid for by the reporting company. Road freight is the dominant mode within it for most organisations: the trucks that carry raw materials inbound and move stock between distribution centres.

Category 4 vs Category 9 — same factors, different direction

The distinction between Category 4 and Category 9 is the direction of the goods flow, not the calculation. Category 4 is upstream — transport the reporting company pays for, bringing goods in. Category 9 is downstream — transport of sold products after they leave the company’s control. The GLEC road intensities are identical across both; the calculator computes the emissions the same way, and the only editorial difference is which category line the result is booked to. A logistics provider reporting its own fleet emissions books them to Scope 1; a shipper paying that provider books the same tonne-km to Scope 3 Category 4.

Asset-class boundary — what’s in, what’s elsewhere

How the calculation works — tonne-km × WTW intensity

Each leg of a road-freight movement reduces to one multiplication, run per leg and summed at the shipment or portfolio level:

Freight emissions (kg CO₂e) = Mass (tonnes) × Distance (km) × WTW intensity (kg CO₂e per tonne-km)

The activity-data spine — mass × distance = tonne-km

The tonne-kilometre is the unit that makes freight emissions comparable across modes and vehicles. Ten tonnes carried 100 km and one tonne carried 1,000 km are both 1,000 tonne-km and, on the same vehicle, carry the same emissions. The calculator takes cargo mass in tonnes and leg distance in kilometres as the two activity inputs; the product is the tonne-km the intensity factor multiplies. Where a journey has distinct legs — a 600 km trunk haul followed by a 40 km regional delivery on a smaller vehicle — each leg is entered separately with its own class and distance, because the intensity differs by vehicle.

Well-to-wheel, well-to-tank, tank-to-wheel

GLEC reports each road intensity as a well-to-wheel value — the full lifecycle of the fuel from extraction to combustion. It decomposes into two parts:

Region selection — four sets, never blended

GLEC v3.2 carries four regional road sets, and the calculator keeps them separate. The selection axis differs by region: Europe and South America share a class × load × fuel matrix; North America uses a flat US EPA SmartWay segment shape. Select the region where the leg physically runs.

Choosing the right truck class and load factor

The two regional shapes ask for different inputs, and getting the class selection right is the difference between a defensible figure and a placeholder.

The North American package segment running at 1.272 kg CO₂e/tonne-km is not an error — small-parcel networks carry low payload per vehicle-km relative to their distance, so the per-tonne-km intensity is an order of magnitude above trunk haulage. Where a North American leg is genuinely small-parcel, the package segment is correct; where it is full-truckload trunking, the truckload dry van segment at 0.093 kg CO₂e/tonne-km is the match.

Diesel, electric, and bio-LNG — the fuel pathway comparison

For an articulated tractor in the 34–40t class moving the same payload over the same distance, the fuel pathway changes the per-tonne-km intensity by a factor of nearly six. The chart below compares the three EU/SA pathways for that class on a like-for-like payload basis.

Bio-LNG is the lowest-carbon pathway in the set because the biogenic feedstock displaces fossil natural gas in the well-to-tank component. The GLEC intensity of 0.038 kg CO₂e/tonne-km reflects the lifecycle of the bio-LNG supply chain, not a zero-rating of the biogenic combustion — a distinction worth holding when reconciling against frameworks that treat biogenic CO₂ separately.

Why load factor decides the result

Within a single truck class and fuel, the load factor is the largest single driver of per-tonne-km intensity. A vehicle’s fuel burn is relatively insensitive to payload — an empty truck still burns most of the fuel a full one does — so spreading that burn over a smaller payload raises the per-tonne-km figure sharply. The chart below shows the effect for a representative rigid class across the GLEC laden states.

The chart is illustrative of the direction and magnitude of the effect rather than exact ratios, which vary by class. The practitioner consequence is concrete: a haulage operation that runs dedicated outbound loads and empty returns should account for the empty-running explicitly, because booking the whole journey at average laden understates the backhaul emissions. Where the operation balances loads in both directions, the average laden state is the appropriate default.

Worked example — a four-leg multi-region road shipment

This example reproduces against the live calculator. The shipment is a single consignment routed across two regions on three vehicle types and two fuels — the realistic shape of an intermodal supply leg where road handles the first and last segments. All factors are GLEC Framework v3.2 well-to-wheel intensities; the well-to-tank and tank-to-wheel components are shown where GLEC publishes them.

Inputs

Leg-by-leg calculation

* Share column sums to 94.7% because the four leg shares are rounded to one decimal place; the underlying totals reconcile to 100%.

The 650 km EU diesel trunk haul dominates at 53.3% of the shipment footprint — long-distance, full-payload trunking carries the most tonne-km even at the lowest per-tonne-km intensity of the diesel legs. The electric shuttle, despite being the “low-carbon” leg, contributes 8.8% on only 1,080 tonne-km because its WTW intensity (grid upstream) is more than double the diesel artic’s. This is the reporting reality the WTW basis surfaces: the electric leg is not free, and over a short distance with modest payload it still books a non-trivial figure.

Shipment rollup

The blended shipment intensity of 0.109 kg CO₂e/tonne-km sits close to the diesel artic figure because the trunk haul dominates the tonne-km. Tracking this blended intensity over time is the cleanest decarbonisation signal for a road-freight programme — it isolates the carbon efficiency of the transport from the volume of goods moved, so a falling blended intensity reflects genuine modal or load-factor improvement rather than simply shipping less.

Data quality and the GLEC default hierarchy

GLEC frames freight data quality as a hierarchy from primary measured energy down to modelled defaults, and the calculator supports the full range. The reporting expectation is to climb the hierarchy where the emissions are material, not to apply the highest-precision method everywhere.

The honest disclosure is the mix: a road-freight inventory that runs primary activity data on its top-20 lanes and modelled defaults on the long tail is a defensible, well-constructed inventory. Claiming primary-energy precision across every leg when most are modelled defaults is the disclosure failure, not the use of defaults itself.

Audit checklist — what gets flagged in freight assurance

Freight assurance under ISO 14083 and ISAE 3000 traces each leg from activity data to the rolled-up total. The findings below are the most common substantive issues raised on a road-freight inventory specifically.

Reporting context — Scope 3, GLEC/ISO 14083, IFRS S2, CSRD

Road-freight emissions feed several disclosure regimes through the same underlying GLEC calculation. The four frameworks below cover the disclosure surface a typical shipper or logistics provider navigates.

GLEC and ISO 14083 — the convergence

The GLEC Framework and ISO 14083 have converged: GLEC v3.2 is structured to align with the ISO 14083 transport-chain emissions methodology, so a calculation built on GLEC intensities is also broadly ISO 14083-conformant. This matters for assurance — an ISO 14083 reference in a methodology statement signals an internationally standardised basis rather than a proprietary one, which assurers and disclosure regimes increasingly expect for transport emissions.

Data sources, factor versioning, and update transparency

Road intensities — source and structure

The road-freight intensities are drawn from GLEC Framework v3.2, retrieved for the MasterBrain factor set in May 2026. The set carries 125 road rows across four regions: Europe/South America (50 rows, class × load × fuel plus weight-band summaries), China (51 rows), North America (14 SmartWay segments), and India (10 rows). Each row’s headline value is the well-to-wheel intensity on an AR6 GWP-100 basis. The well-to-tank and tank-to-wheel components are published alongside each row and are reported in worked examples as fixed component pairs — they are not user-variable inputs. See the DEFRA emission factors reference for the UK road and fuel factors that complement the GLEC set for own-fleet legs.

GWP basis

The GLEC road set uses AR6 GWP-100 — the IPCC Sixth Assessment Report’s 100-year global warming potentials. This is the current GLEC convention and aligns with the GHG Protocol’s expected basis. Where a road-freight inventory is combined with DEFRA-sourced own-fleet legs, note that DEFRA factors are published on an AR5 GWP-100 basis; the calculator does not silently reconcile the two, and a mixed-basis inventory should disclose the mix rather than implying a uniform basis. See the global warming potential definition for the AR5-to-AR6 distinction.

Versioning and update cadence

GLEC publishes factor refreshes annually, and the MasterBrain factor set tracks each publication. The calculator stamps each result with the MasterBrain version against which it was computed, so a leg computed against one factor vintage and the same leg recomputed against a later vintage are distinguishable in restatement work. GLEC Framework version (v3.2) is independent of the underlying factor vintage — a methodology version applies across successive annual factor refreshes until the next framework revision ships.

What’s next — completing your Category 4 transport inventory

Road freight is the dominant mode in most upstream-transport inventories, but a complete Category 4 footprint spans every mode a supply chain uses. The other freight modes follow distinct factor sets — per-TEU-km for sea container, jet-fuel intensities for air, traction-and-commodity profiles for rail — and each requires its own calculator. The following modes are on the GreenCalculus build roadmap; none is published yet.

Separately from the upstream Category 4 modes above, downstream transport and distribution (the movement of sold products after they leave the company’s control) is accounted under Scope 3 Category 9, not Category 4. It uses the same GLEC road intensities but books to a different category line. A dedicated downstream transport calculator is on the roadmap and is not yet published.

Quick converter: g CO₂e/tonne-km to per tonne-mile.

Frequently asked questions

Methodology notes and limitations

Methodology version. Calculator implements the GLEC Framework v3.2 road-freight intensities (retrieved May 2026), aligned with ISO 14083. Results are computed on an AR6 GWP-100 basis. Inventories computed against earlier factor vintages remain auditable against the corresponding MasterBrain version stamp.

Mode boundary. Road freight only — heavy and medium goods vehicles, rigid and articulated, across the four GLEC regional sets. Sea, air, rail, inland-waterway, last-mile, and cold-chain freight use separate factor sets and unit bases and are out of scope for this tool.

Unit basis. Intensities are per tonne-kilometre. This is distinct from the per-kilometre basis used for last-mile and small-vehicle delivery. The calculator does not convert between the two, and a per-km factor must never be applied to a tonne-km leg.

WTW headline; WTT/TTW fixed components. The calculator computes the well-to-wheel total. The well-to-tank and tank-to-wheel components are published by GLEC alongside each row and are reported in worked examples as fixed pairs; they do not vary with user inputs and are not separate live fields.

Electric and alternative fuels. Battery-electric intensities are the upstream grid emissions of the charging electricity (full intensity in WTT, TTW zero) and are not zero on a WTW basis. Bio-LNG intensities reflect the lifecycle of the bio-LNG supply chain. Both are per-leg fuel selections, not portfolio-wide assumptions.

Region not blended. The four regional road sets are kept separate. Each leg is factored against the region where it physically runs, and the EU/SA class shape and North American SmartWay segment shape are not interchangeable.

Activity data taken as entered. The calculator uses the mass, distance, and load factor the user enters; it does not independently verify them. The user is responsible for the activity-data basis — actual versus estimated distance, measured versus assumed load — and for documenting it per leg.

No assurance opinion. Results are estimates and do not constitute an assurance opinion. They should be reviewed by a qualified practitioner before use in IFRS S2 disclosures, CSRD ESRS E1 datapoints, or other regulatory submissions. The full methodological deep-dive — region-set selection trees, load-factor derivation, and the WTT/TTW decomposition — is published on the paired GLEC road-freight methodology page.