How flight emissions are estimated
A flight’s footprint per passenger depends mostly on the distance, because fuel burn grows with every mile, and on how much cabin space each passenger occupies. This calculator uses emission factors per passenger-kilometer from ADEME, the French environment agency, which include the extra warming from contrails and nitrogen oxides at altitude:
| Flight distance (one way) | kg CO₂e per passenger-km | Typical example |
|---|---|---|
| under 1,000 km (620 mi) | 0.258 | Boston to Washington |
| 1,000 to 3,500 km | 0.187 | Chicago to Miami |
| over 3,500 km (2,175 mi) | 0.152 | New York to London |
Short flights emit more per mile because takeoff and climb burn a large share of the fuel.
Cabin class factors: premium economy × 1.6, business × 2.9, first × 4, reflecting the floor space each seat takes.
Worked example
A round trip from New York to Los Angeles, about 2,450 miles (3,940 km) each way, in economy, for one passenger:
- Long-haul factor: 0.152 kg CO₂e per km.
- One way: 3,940 × 0.152 = 599 kg.
- Round trip: 1,199 kg, about 2,640 lb or 1.20 tonnes of CO₂e.
- That is about 60% of a 2-tonne yearly climate budget per person.
- It equals driving an average gas car about 3,000 miles, at 400 g of CO₂ per mile.
- A mature tree absorbing 22 kg a year would need one year for every 22 kg, so about 54 trees for a year.
Putting it in perspective
| Activity | Approximate CO₂e |
|---|---|
| Average American footprint, per year | 15 to 16 tonnes (energy-related CO₂) |
| Climate-compatible target for 2050 | about 2 tonnes per person |
| New York to London round trip, economy | about 1.7 tonnes |
| Same trip in business class | about 4.9 tonnes |
Reducing your flight footprint
- Fly less, stay longer: one long trip instead of several short ones.
- Choose economy: it divides your share of the emissions by about 3 compared with business.
- Fly direct: extra takeoffs and longer routings add fuel.
- Take the train for short trips: for trips under about 500 miles, rail usually emits a fraction of a flight.
- Offsets can fund useful projects, but their quality varies and they do not remove the emissions of the flight itself.
Factors differ between methods: some exclude non-CO₂ effects, which roughly halves the result, and real emissions depend on aircraft type, load factor and route. Treat the result as an order of magnitude.