How to use
- 1Pick the route by airport (city, IATA or ICAO), or switch to Distance and enter the km.
- 2Choose the cabin class — economy, premium economy, business or first — and the number of passengers.
- 3Select one way or round trip, and tick radiative forcing (×1.7) if you want non-CO₂ effects included.
- 4Read the CO₂e per passenger and in total, the factor used, and the car and tree comparisons.
Method: UK DESNZ 2025 conversion factors
The calculator uses the air travel factors from the UK Government’s "Greenhouse gas reporting: conversion factors 2025" (DESNZ), the same set many organisations use for business travel reporting. Distance is the great-circle distance between the airports; the 8% uplift for indirect routing and holding is already built into the factors. Flights fall into three bands: under 500 km, under 3,700 km (short-haul) and 3,700 km or more (long-haul). The kg CO₂e per passenger-km factor for the band and cabin is multiplied by the distance — London to New York in economy comes to about 384 kg CO₂e one way.
Why cabin class and radiative forcing matter
Premium seats take up more floor space, so each passenger is allocated a larger share of the aircraft’s emissions: on long-haul, the business factor is nearly three times the economy one. DESNZ publishes no premium economy or first factors for short-haul, so economy and business are used there. The radiative forcing option applies the 1.7 multiplier DESNZ recommends to account for non-CO₂ effects at altitude, such as contrails and nitrogen oxides. The science behind these effects is still uncertain, which is why the option is kept separate.
Comparisons and limitations
The result is compared with driving an average car (DESNZ 2025: 0.167 kg CO₂e per km) and with tree-years, assuming a mature tree absorbs about 22 kg of CO₂ a year (European Environment Agency, indicative). These figures are estimates: aircraft type, load factor, cargo and the actual route all change real emissions. Use them to compare routes, cabins and trip options, or as a starting point for travel reporting.
Frequently asked questions
How much CO₂ does a flight produce per passenger?
It depends on distance and cabin. In economy, London to New York is about 384 kg CO₂e one way and Dubai to London about 381 kg, excluding radiative forcing.
Should I include radiative forcing?
Include it to see the wider climate impact of flying; results rise by about 1.7×. Many reports show both figures side by side.
Is business class really worse for the climate?
Per passenger, yes. A business seat takes more space, so on long-haul flights its share of emissions is roughly three times that of an economy seat.
Does the result depend on the airline?
No. The factors are averages across aircraft and load factors; airline, aircraft type and fleet age are not taken into account.
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