Advanced options
Based on DEFRA-style emission factors per passenger-km, including an uplift for non-CO2 effects at altitude, with class multipliers reflecting cabin space. Rough distances: London-Edinburgh 530km, London-Malaga 1,700km, London-New York 5,570km, London-Sydney 17,000km.
What The Flight Carbon Calculator Works Out
- CO2e per passenger: distance multiplied by a government (DEFRA) conversion factor per passenger-kilometre, roughly 0.15 kg for short and long haul and about 0.25 kg for domestic hops (take-off dominates short flights), multiplied up for premium cabins. A return economy trip to southern Europe comes out near half a tonne.
- Share of a UK annual footprint: the flight as a percentage of a typical UK resident's 6 tonnes a year. A return long-haul in business class can exceed an entire monthly footprint several times over.
- For scale: the kilometres an average petrol car (0.17 kg CO2e per km) would cover for the same emissions.
- Distance in miles (advanced): enter the distance in miles instead of kilometres; it is converted at 1.609 km per mile.
- Total for your party and per year (advanced): the per-passenger figure multiplied by passengers, then by how often you make the trip. A family of four flying to Spain twice a year is close to 4 tonnes, more than most of their other choices combined.
- Cost to offset (advanced): tonnes multiplied by an offset price. Verified credits typically cost GBP 10 to GBP 25 a tonne; schemes vary from rigorous to decorative, and the factors here are the sober way to know the size of what is being offset.
- Same journey by train (advanced): the distance at the national rail factor of about 0.035 kg per passenger-km, roughly a quarter of the flight. London to Edinburgh by train or Eurostar to Paris undercut the plane by an order of magnitude.
- Same journey by car (advanced): one petrol car at your mpg carrying the whole party, using 2.31 kg CO2 per litre. A full car over a short-haul distance can beat flying; a solo driver rarely does.
- Custom emission factor (advanced): override the built-in factor with an airline's or route's own figure if you have one. Direct routing, fuller and newer aircraft all genuinely reduce the per-passenger number.
- Cabin class table (advanced): the same flight in every class. In accounting terms the same passenger emits nearly three times as much turning left as turning right, because a business seat occupies two to three economy seats' worth of aircraft. The factors include an uplift for non-CO2 effects, since contrails and nitrogen oxides at altitude roughly double aviation's warming impact.
Source and further reading: GOV.UK: greenhouse gas conversion factors.