Work out your car mileage emissions
= 5.97 tonnes CO2e in 2026 (Scope 3)
Each vehicle-mile × 0.2986 kg CO2e, the 2026 GHG Emission Factors Hub figure (Cornerstone) for "Passenger Car", CO2, CH4 and N2O combined.
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Passenger car: emission factor by Hub edition (per vehicle-mile)
From Table 10, Scope 3 Category 6 and 7: Business Travel and Employee Commuting, row "Passenger Car". The Hub publishes the three gases separately; the kg CO2e column adds them up with the global warming potentials (GWPs) each edition states.
| Edition | kg CO2 | g CH4 | g N2O | GWPs (CH4, N2O) | kg CO2e per vehicle-mile | Change |
|---|---|---|---|---|---|---|
| 2026 (Cornerstone) | 0.2970 | 0.005900 | 0.005300 | 27, 273 | 0.2986 | +0.01% |
| 2025 (EPA) | 0.2970 | 0.005900 | 0.005300 | 28, 265 | 0.2986 | -3.1% |
| 2024 (EPA) | 0.3061 | 0.008986 | 0.006013 | 28, 265 | 0.3080 | -2.3% |
| 2023 (EPA) | 0.3130 | 0.008000 | 0.007000 | 25, 298 | 0.3153 | – |
The gases changed between editions as the Hub updated its source data, and the GWPs changed too (2023: CH4 25, N2O 298 (IPCC AR4); 2024: CH4 28, N2O 265 (IPCC AR5); 2025: CH4 28, N2O 265 (IPCC AR5); 2026: CH4 27, N2O 273 (IPCC AR6, non-fossil CH4)). Source: US EPA, GHG Emission Factors Hub (2023-2025 editions, public domain) and Emission Factors Hub 2026, Cornerstone Sustainability Data Initiative, CC BY 4.0.
Worked example
Take staff claiming 20,000 vehicle-miles a year. 20,000 vehicle-miles × 0.2986 kg CO2e = 6.0 tonnes CO2e, reported as Scope 3, Category 6 (business travel). In metric units the factor is 0.1855 kg CO2e per vehicle-km (one mile is exactly 1.609344 km).
How to use it
Multiply business miles by the factor and report the total as Scope 3, Category 6 (business travel). Employee commuting in the same vehicles goes in Category 7 instead. The GHG Protocol's Scope 3 Standard counts both as optional for many reporters, but customers asking for supplier data increasingly expect them.
The Hub defines a passenger car as an automobile for up to 12 people weighing under 8,500 lb. This is an average for the US car fleet, per vehicle-mile, so it does not change with the number of people in the car. For cars the company owns or leases, report the fuel bought as Scope 1 instead.
The usual mistake is double counting. Miles in cars and trucks the company owns or leases belong in Scope 1, worked out from the fuel bought; only miles in employees' own or hired vehicles go here, in Scope 3. The other is units: these figures are per mile, so convert kilometres first (divide by 1.609344).
UK companies with sites, staff or shipments in the US can use these figures for that activity, and the UK government factors for activity in the UK (see the UK government factor for the same activity). Say in your methodology which set you used for which activity. In Carbon Recycling, every line keeps the factor and source it was worked out with.
Where to find your vehicle-mile figure
Mileage claims or expense reports. Use miles driven on business in cars the company does not own or lease.
Who publishes the 2026 figures
The GHG Emission Factors Hub was published by the US EPA's Center for Corporate Climate Leadership every year up to the January 2025 edition, as a US government work in the public domain. The 2026 edition, last updated 26 May 2026, was published by the Cornerstone Sustainability Data Initiative, not by EPA, under a CC BY 4.0 licence (doi:10.5281/zenodo.20403776). It keeps EPA's table layout and its footnotes cite the same sources, such as 40 CFR Part 98 and EPA's Inventory of US Greenhouse Gas Emissions and Sinks. EPA has not endorsed it.