Flight CO2 Calculator
Estimate the carbon footprint of a flight from distance, cabin class and trip type, with an optional high-altitude multiplier and trees-to-offset figure. Calculates in your browser.
Per passenger
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Show the math
Emissions scale with distance times an emission factor (kg CO₂e per passenger-km) for the haul and cabin class:
CO₂e = great-circle distance × factor(haul, cabin, RF) × (2 if round trip)
Factors are the UK government's 2025 conversion factors (DESNZ): flights under 3,700 km use the short-haul set, longer ones the long-haul set (DESNZ's distance rule of thumb; it now prefers sorting flights by destination region). Premium cabins take more space, so they carry a bigger share of the plane's footprint (short-haul figures exist only for economy and business, so premium and first use business). Including high-altitude effects switches to DESNZ's "with RF" factors, which multiply the CO₂ part by 1.7. One mature tree absorbs about 22 kg (48 lb) of CO₂ a year.
Estimates use typical load factors and vary by aircraft. Everything is calculated in your browser.
What this does
A flight CO₂ calculator estimates the carbon footprint of a flight from distance, cabin class, and trip type, with an optional high-altitude multiplier and trees-to-offset figure.
How to use it
- Enter the flight distance.
- Choose the cabin class.
- Pick one-way or round trip.
- Read the estimated emissions.
How it works
Distance times a per-passenger-km factor for the haul and cabin class sets the figure, using the UK government’s 2025 (DESNZ) conversion factors; the optional high-altitude setting uses their “with RF” factors, which multiply the CO₂ part by 1.7.
CO₂e = distance × factor(haul, class) × trip
Understanding your result
The figure is an estimate, and two choices move it most: cabin class, since premium seats take a larger share of the plane, and the altitude setting, which raises the total by roughly 70% when included. The most effective reductions are flying less, flying direct, and choosing economy; treat offsets as a partial measure rather than a cancellation of the emissions.
Example
A 5,000 km economy round trip is about 0.69 metric tons CO₂e (5,000 × 0.06926 × 2), or about 1.17 metric tons with high-altitude effects included.
Last updated .
Frequently asked questions
How are flight emissions estimated?
Distance is multiplied by an emission factor (kg CO₂ per passenger-km) that varies with haul length, then adjusted for cabin class and whether it is a round trip.
Why does cabin class change the result?
Premium seats take up more space, so each passenger carries a larger share of the plane’s footprint, business is roughly three times economy.
What is the high-altitude multiplier?
Emissions at altitude cause extra warming beyond the CO₂ itself. The optional setting uses DESNZ’s “with RF” factors, which apply a 1.7 radiative-forcing multiplier to the CO₂ part to account for these non-CO₂ effects.
Is my data kept?
No. Everything is computed locally in your browser.
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