Business travel emissions factors 2026: flights, rail and hotels

The SECR guidance and the Carbon Reduction Plan standard for government bids both point to the same spreadsheet for turning business travel into carbon: the UK Government’s greenhouse gas conversion factors, published by DESNZ. The 2026 set came out in June 2026 and the next is due in June 2027. This page extracts the three business travel tabs from the 2026 set (flights, land travel and hotel stays), explains the choices that change the answer, chiefly whether to include the indirect effects of flying, and gives a calculator built on the same numbers.

Flights: the 2026 factors

“Air conversion factors should be used to report Scope 3 emissions for individuals flying for work purposes.” DESNZ publishes two sets. One counts only the direct greenhouse gases from burning fuel; the other adds the indirect effects of emissions at altitude — water vapour, contrails and nitrogen oxides — usually called radiative forcing (RF).

What the hauls mean: “Broadly speaking the definition of domestic flights, are those within the UK, short-haul are those within Europe, long-haul are outside of Europe and international flights are those between non-UK destinations.” The workbook includes a sheet assigning each country to a haul band. Two further points are built into every figure: “All the factors include the distance uplift of 8% to compensate for planes not flying using the most direct route”, and class is allocated by floor space — “Air travel factors are calculated on the basis of the area of the plane each passenger takes up.” On the long-haul figures, business class is 2.9 times economy.

Radiative forcing: include it, and be consistent

The same guidance is candid that “there is significant scientific uncertainty around the magnitude of the indirect effect of non-CO2 aviation emissions”. Its practical instruction is about comparability: “they should avoid reporting emissions including indirect effects of non-CO2 emissions in one year and direct effects only in another year” as this may skew the interpretation of the reporting. A policy that states which set it uses, and a supplier report that labels its figures, prevents most of the confusion between years and between suppliers.

How DESNZ expects the data to be collected

The workbook’s own worked example is about a travel agent: “To do so it requests a report from its dedicated travel agent, which reports the distances travelled for domestic, short-haul and long-haul flights, in each class of travel (ranging from economy to first class).” Where class is missing, “Where the ‘haul’ of the journey is known, but the class is unknown, the company uses the ‘average passenger’ factor.” On spending data it is blunt: “There are no confirmed industry benchmarks that provide accurate CO2e/£ spend data for air travel.” Distance by haul and class is therefore the field to ask a travel supplier for; a figure in tonnes without the distances behind it cannot be checked.

Rail, taxis, coaches and cars

The land tab covers travel in vehicles the organisation does not own or operate: “This includes mileage for business purposes in cars owned by employees, public transport, hire cars, and so on.” Mass transport is per passenger-km; a whole car or taxi hired for the journey is per vehicle-km. The 2026 set refreshed the rail figures with Office of Rail and Road data, replacing factors last updated in 2021.

Per 1,000 km, side by side

The car figure is for the vehicle, so two colleagues sharing halve it per person; the rail and flight figures are already per passenger. A domestic flight with RF is about 7 times national rail per passenger-km on these factors.

Hotel stays

“The conversion factors provided are for an average class of hotel and can be applied to a stay at any type of hotel.” Factors are per room per night: “The conversion factor does not differentiate for number of travellers staying in the room.” “The hotel stay conversion factors are taken from the Hotel Footprinting Tool”, produced by the International Tourism Partnership and Greenview. Countries without a 2026 factor are not listed below; DESNZ says users may continue to use the last available factor for them.

Where these factors are required

• SECR. Large unquoted companies must report fuel for business mileage in employees’ own and hire cars where they pay for the fuel; flights, rail and hotels are voluntary Scope 3. See SECR and business travel.
• Carbon Reduction Plans for central government contracts over £5 million a year must include business travel as one of five Scope 3 categories, and the technical standard requires emissions to be calculated “using the appropriate conversion factors published by the UK Government”. See Carbon Reduction Plans.
• Supplier reports. Ask which factor year and which air set (with or without RF) a report uses, and for the distances by haul and class behind it.

This page reproduces factors from the UK Government’s 2026 set, published under the Open Government Licence, as read on 2026-10-03. The 2027 set is due in June 2027. Air travel policy choices — class and rail-first rules — are on corporate travel policy.

Common questions