Flight distance is a key input for carbon footprint calculations. Understanding the methodology helps build accurate sustainability features and carbon offset tools.
Emissions Per Distance
Average CO2 emissions are roughly 90g per passenger per kilometer for short-haul, 100g/km for long-haul flights. Actual emissions depend on aircraft type, load factor, seat class, and routing efficiency. First/business class has higher per-passenger emissions due to space usage.
Distance Factors
Takeoff and landing are the most fuel-intensive phases. Short flights have proportionally higher emissions per km. Non-stop flights are more efficient than connections because each takeoff/landing cycle adds fuel burn. Direct distance underestimates actual flight path by 5-10%.
Radiative Forcing
CO2 is not the only climate impact. Contrails and NOx emissions at altitude have additional warming effects. The IPCC multiplier (typically 1.9-2.0) accounts for these non-CO2 effects. Some calculators include this; others show CO2 only—be clear which you display.
Building Carbon Calculators
For user-facing tools, use distance as the primary input. Apply a reasonable average emission factor (250-300g CO2 per km for round-trip, including radiative forcing). More accurate calculators incorporate aircraft type, airline data, and seat class.