Flight CO2 Emissions Calculator
Calculate the greenhouse gas emissions (CO2 equivalents) from a flight, based on distance, number of passengers, and whether the trip is round-trip.
How to use the calculator
- Enter the one-way flight distance in kilometers.
- Enter the number of passengers the trip is for.
- Check the box if the trip is round-trip.
How it's calculated
The calculator uses DEFRA's (the UK government's official carbon reporting factors) 2026 emission factors for economy class, including radiative forcing for high-altitude effects. Short flights (under 3700 km) have a slightly higher emission factor per kilometer than long ones, since a larger share of the flight is spent on fuel-intensive take-off and climb.
Cabin class and load factor change emissions per passenger
An aircraft's emissions are shared among the passengers on board, and how large a share each person carries depends on how many are sharing it. A flight with a low load factor produces higher emissions per passenger than a full flight on the same route. Standard emission factors are therefore built on industry-average load factors rather than on any individual departure.
Cabin class matters sharply for the same reason. A business or first class seat occupies several times the floor area of an economy seat, and is allocated a correspondingly larger share of the aircraft's emissions — in standard methodology often two to four times as much. This calculator uses an economy class factor, so if you travel in another class your real footprint is higher.
Frequently asked questions
Why do short flights have higher emissions per km than long ones?
Because take-off and climb use a lot of fuel regardless of total trip length — on a short flight, this phase makes up a larger share of the whole trip than on a long one.
What does "radiative forcing" mean?
Aircraft emit more than just CO2 at high altitude — contrails and other effects also contribute to warming. The radiative forcing multiplier in the emission factor accounts for this extra climate effect, not just the CO2 itself.
Can I compare this to driving?
Yes, roughly — see the vehicle CO2 emissions calculator for a comparable per-kilometer figure.