How CO₂ reporting works
CO₂ reporting in transport calculates how much greenhouse gas a shipment, trip or fleet emits — and expresses it in a way customers, auditors and regulators accept. The mechanics are not complicated; the discipline is in making the underlying data clean.
The basic formula
At its simplest:
CO₂ emissions = distance × emission factor × cargo share
- Distance – kilometres driven for the leg.
- Emission factor – kg CO₂(-equivalent) per kilometre for the vehicle and fuel type.
- Cargo share – the portion of the trip allocated to a specific shipment (by weight, volume or stop count).
The factor comes from a recognised dataset (DEFRA, GLEC, EcoTransIT, national equivalents). The distance comes from your trips. The cargo share comes from your shipment structure.
Well-to-Wheel vs Tank-to-Wheel
This is the single most important distinction in transport CO₂ reporting.
| Tank-to-Wheel (TTW) | Well-to-Wheel (WTW) | |
|---|---|---|
| Scope | Combustion only (what comes out of the exhaust) | Combustion plus fuel production, transport and refining |
| Typical share | ~75% of WTW | 100% |
| Required by | Older fleet KPIs, some internal benchmarks | CSRD, GLEC Framework, most customer ESG reports |
| Risk if you only do TTW | You under-report by ~25% | None |
Routix calculates both WTW and TTW per shipment and per trip, using a configurable emission factor per vehicle and fuel type. See Emissions.
What you need to report properly
- Trip data – start, end, distance, vehicle.
- Vehicle data – fuel type, Euro class, kg CO₂/km (or kg CO₂/litre + consumption).
- Shipment data – weight or volume per shipment so you can allocate per cargo.
- A consistent allocation rule – weight-based, volume-based, stop-based, or t·km-based. Pick one and stay with it.
- A reporting period – month, quarter, year, customer, lane.
Without (1)–(3) you can produce a number, but not one that survives an audit.
CSRD and GLEC, briefly
- CSRD (EU Corporate Sustainability Reporting Directive) requires large EU companies to report Scope 1, 2 and 3 emissions. Transport bought from carriers is Scope 3 for the shipper — meaning your customer will ask you for the data.
- GLEC Framework is the industry standard for how to calculate transport emissions. CSRD-aligned reports usually follow GLEC.
- ISO 14083 is the international standard built on top of GLEC; it’s becoming the reference for transport emissions.
If you’re a carrier or forwarder, you don’t need to be a CSRD entity yourself — but your customers will increasingly require GLEC/ISO 14083-compatible data from you.
Common mistakes
- Only reporting TTW. Under-reports actual climate impact by roughly 25%. Customers and auditors notice.
- Averaging fuel for the whole fleet. Hides the high-emitting vehicles. Calculate per vehicle if you can.
- Forgetting empty kilometres. Empty legs still emit — and they belong in the report. See empty miles.
- Allocating per shipment count, not per t·km. A 50 kg parcel and a 24-ton load can end up with the same emissions. Use a weight- or distance-weighted allocation.
- Spreadsheet at year-end. Numbers are stale and inconsistent. Calculate per trip, in the operational system.
How Routix handles it
- Emission factors stored per vehicle and fuel type.
- WTW and TTW calculated on every trip and shipment automatically.
- Allocation per shipment based on weight or volume.
- Dashboard per period, customer, vehicle and branch.
- Export-ready for customer ESG questionnaires.
See the Emissions dashboard.
Related concepts
See this in Routix
If you want this calculation without spreadsheet work, start on www.routix.com and then open the Emissions dashboard in Routix. That is where trip data, shipment allocation and WTW versus TTW reporting are shown from the operational record.
