Flight Carbon Footprint Calculator
The carbon footprint of a flight depends on the distance flown, the number of passengers sharing the trip, the emission factor per passenger-kilometre and an optional radiative forcing multiplier that captures the extra warming effect of emissions at altitude. Because published emission factors differ by source, aircraft and cabin class, this calculator keeps both the emission factor and the multiplier as editable inputs so you can match the figure from your chosen government or official authority. Enter the one-way distance, choose whether to count a return trip, and read the total CO2 equivalent and the per-passenger share.
Flight carbon footprint formula
Total distance = one-way distance * (return ? 2 : 1)
Per passenger CO2e = total distance * emission factor * RF multiplier
Total CO2e = per passenger CO2e * passengers
Tonnes = total CO2e / 1,000
The emission factor is the CO2 equivalent released per passenger for each kilometre flown. The radiative forcing multiplier scales that figure to reflect the additional warming impact of aviation emissions at altitude. Set the multiplier to 1.0 to report CO2 only.
Using a sourced emission factor
- The factor varies by haul length: short, medium and long-haul flights have different per-kilometre intensities.
- Cabin class matters: premium seats are assigned a larger share of the aircraft's emissions.
- The radiative forcing multiplier is debated; report it transparently or set it to 1.0 for CO2 only.
- Use great-circle distance between airports for the one-way figure.
- Always cite the source and year of the emission factor you enter.
Flight carbon footprint: frequently asked questions
How is a flight carbon footprint calculated?
Multiply the flight distance in kilometres by an emission factor in kilograms of CO2 equivalent per passenger-kilometre, then apply a radiative forcing multiplier to account for the extra warming impact of emissions at altitude. This calculator keeps the emission factor and multiplier as editable inputs so you can match the figure published by your chosen authority.
What emission factor should I use per passenger-kilometre?
Published per-passenger-kilometre factors vary by aircraft, route length and cabin class. The UK Department for Energy Security and Net Zero (DESNZ) publishes annual greenhouse gas conversion factors for business reporting, and the US EPA publishes emission factors for transport. Enter the factor from your chosen source. A short-haul economy figure is often near 0.15 kg CO2e per passenger-km, but you should confirm the current figure from the source.
What is the radiative forcing multiplier?
Aviation emissions at high altitude have warming effects beyond CO2 alone, including contrails and nitrogen oxides. Some reporting frameworks apply a multiplier (often quoted between 1.0 and 1.9) to reflect this. Because the exact value is debated and source-dependent, it is a user-editable input here. Set it to 1.0 to report CO2 only.
Does cabin class change the footprint?
Yes. Premium and business seats occupy more floor area per passenger, so reporting frameworks assign them a higher share of the aircraft's emissions. Use the per-passenger-kilometre factor that matches your cabin class from your chosen authority.
Official sources
- UK Department for Energy Security and Net Zero: Greenhouse gas reporting: conversion factors.
- U.S. Environmental Protection Agency: GHG Emission Factors Hub.
Reviewed by the CalculatorHub team, edited by James Graham, 19 June 2026. See our methodology.