Travel Calculators · UK DESNZ 2026 factors
Flight carbon footprint calculator.
Choose two airports, a cabin class and one way or round trip. You get kg CO2e per passenger from the UK government's 2026 conversion factors, with and without radiative forcing. Runs locally; nothing is transmitted.
Inputs
Result
Fill the form and press Calculate.
How the flight footprint is calculated
The tool finds the great-circle distance between the two airports and multiplies it by the UK government's emission factor for that route type and cabin class. Class multipliers in the result table are each class's factor divided by the economy factor for the same route type.
Formula
- Distance: haversine great-circle distance, Earth radius 6,371 km, between airport coordinates.
- Emissions: kg CO2e = distance (km) × factor (kg CO2e per passenger-km) × 1 or 2 (round trip) × passengers.
- Uplift: DESNZ states all its air factors already include an 8% distance uplift for indirect routings and stacking, so no extra uplift is applied.
- Route type: UK to UK is domestic; one UK end is short-haul or long-haul by the other country's DESNZ haul definition; no UK end uses the international factors.
2026 factors used (kg CO2e per passenger-km)
| Route type | Class | With RF | Without RF |
|---|---|---|---|
| Domestic | Average | 0.22928 | 0.13552 |
| Short-haul | Average | 0.12786 | 0.07559 |
| Short-haul | Economy | 0.12576 | 0.07435 |
| Short-haul | Business | 0.18863 | 0.11152 |
| Long-haul | Average | 0.15282 | 0.09043 |
| Long-haul | Economy | 0.11704 | 0.06926 |
| Long-haul | Premium economy | 0.18726 | 0.11081 |
| Long-haul | Business | 0.33940 | 0.20083 |
| Long-haul | First | 0.46814 | 0.27701 |
| International (non-UK) | Average | 0.14253 | 0.08420 |
| International (non-UK) | Economy | 0.10916 | 0.06449 |
| International (non-UK) | Premium economy | 0.17465 | 0.10318 |
| International (non-UK) | Business | 0.31656 | 0.18701 |
| International (non-UK) | First | 0.43663 | 0.25794 |
Worked example
London Heathrow (LHR) to New York JFK is about 5,540 km. UK to United States is long-haul in the DESNZ haul definition. In economy with radiative forcing the factor is 0.11704, so one way is 5,540 × 0.11704 = about 648 kg CO2e per passenger and the round trip is about 1,297 kg (1.30 tonnes). Without radiative forcing the factor is 0.06926 and one way is about 384 kg. In business class (0.33940) the same one-way trip is about 1,880 kg, 2.9 times economy.
Methodology and limits
- Great-circle distance is not the route flown; the 8% uplift in the DESNZ factors is the allowance for that. Connections are not modelled: enter each leg separately.
- Factors are averages for company reporting, not for a specific aircraft, airline or load. They cover direct emissions only; well-to-tank (fuel production) factors are published separately by DESNZ and are not added.
- Radiative forcing here is DESNZ's flat 70% uplift on CO2. DESNZ itself notes significant scientific uncertainty; use the same setting from year to year.
- Airport coordinates are from OurAirports (public domain). Only large airports with scheduled service and an IATA code in countries listed on the DESNZ haul sheet are included.
Sources
- UK DESNZ and DEFRA: Greenhouse gas reporting, conversion factors 2026, full set, sheets "Business travel- air" and "Haul definition" (published June 2026; next publication June 2027)
- Government conversion factors for company reporting (collection)
- OurAirports open data for airport names and coordinates
Sources checked September 30, 2026. Check the collection page for the current year's factors; this page uses the 2026 set.
Flight carbon footprint FAQ
How is the flight carbon footprint calculated?
Distance in km between the two airports (great-circle, haversine, Earth radius 6,371 km) multiplied by the UK DESNZ 2026 emission factor in kg CO2e per passenger-kilometre for the route type and cabin class, doubled for a round trip. DESNZ factors already include an 8% uplift for real routings, so none is added here.
What does radiative forcing (RF) change?
Flights also warm the climate through contrails, NOx and water vapour. DESNZ's factors with RF raise the CO2 figure by 70% to approximate that; the without-RF factors count only CO2, CH4 and N2O. DESNZ says the science on the size of this effect is uncertain, and advises not switching between the two across years.
Why does business or first class emit more?
DESNZ allocates emissions by the floor area each passenger occupies. A business seat takes more of the cabin than an economy seat, so each passenger carries a larger share of the flight's emissions.
How are domestic, short-haul, long-haul and international decided?
By country, using DESNZ's Haul definition sheet. UK to UK (including Jersey, Guernsey and the Isle of Man) is domestic. A flight with one UK end is short-haul or long-haul according to the other country. A flight with no UK end uses DESNZ's international factors, which are an average of the UK short-haul and long-haul factors.
Does this include well-to-tank or the fuel supply chain?
No. It uses DESNZ's direct flight factors only. DESNZ publishes separate well-to-tank factors for fuel production, which are not added here.
Why do offset sites and airline calculators give different numbers?
Different factors, load assumptions, aircraft types, routings and RF treatment. This tool uses one published government dataset for company reporting and does not model a specific aircraft, load factor or connection. Treat the result as an estimate.
Is anything uploaded?
No. The airport list and factors are in the page and the calculation runs in your browser.
Disclaimer
This is an educational estimate based on published government averages, not a certified carbon account or an offset quote. Actual emissions depend on aircraft, load and routing.