Free flight carbon calculator: estimate CO₂ and CO₂e per passenger by distance, cabin class and radiative forcing, with car and train comparisons.
Aviation's non-CO₂ effects (contrails, NOx, high-altitude water vapour) roughly double the warming of the CO₂ alone. Recommended for full climate impact; toggle off to see direct CO₂ only.
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Air travel is one of the most carbon-intensive things most people do. This flight emissions calculator estimates the per-passenger CO₂ of a single trip from its distance, cabin class and number of passengers — and shows the full climate impact once aviation’s non-CO₂ effects (radiative forcing) are included. Compare it against the same journey by car or train and see how one flight stacks up against a sustainable yearly carbon budget.
Emissions are the flight distance multiplied by a per-passenger-kilometre factor, a cabin-class multiplier and (optionally) a radiative-forcing multiplier. Per-km emissions follow a U-shape by haul: short-haul flights are highest per km because fuel-hungry takeoff and climb dominate a short leg, medium-haul is the most efficient, and long-haul ticks back up because the aircraft must carry the weight of its own fuel. Premium cabins occupy more floor space, so business is about 2.9× and first about 4× an economy seat. Radiative forcing (≈ 1.9×) captures contrails, NOx and high-altitude water vapour, which roughly double aviation’s warming versus CO₂ alone.
Flight Emissions Formula
Individuals weighing the climate cost of a holiday or a specific route before booking.
Frequent flyers tracking and reporting the emissions of work trips.
Estimating attendee or group travel emissions for carbon-neutral events.
Companies estimating Scope 3 emissions from employee business travel.
A single long-haul round trip can rival an entire year’s sustainable carbon budget. Seeing the number in kg makes an abstract impact concrete.
For shorter trips, rail emits a small fraction of flying. The car and train comparison shows exactly when the ground alternative wins.
Business class is about 2.9× economy and first about 4×. Knowing this reframes the true cost of a premium seat.
Quality carbon offsets require knowing your real emissions. This calculator gives you the CO₂e figure to offset.
Aircraft emissions are shared among passengers by the floor space each seat occupies. A business seat takes roughly three times the space of an economy seat, so DEFRA assigns it about 2.9× the emissions; first class is about 4× economy. Flying economy is the single biggest per-passenger lever after not flying.
Beyond CO₂, aircraft warm the climate through contrails, nitrogen oxides that form ozone, and water vapour released at altitude. These roughly double aviation’s warming, so we multiply CO₂ by about 1.9 to get CO₂e. The exact figure is debated (IPCC and the European Environment Agency cite a 1.9–3 range), so we show both the direct CO₂ and the CO₂e-with-RF and let you toggle it.
Takeoff and climb burn far more fuel than cruising. On a short flight that fuel-intensive phase is a big share of the trip, so per-km emissions are highest. Medium-haul flights are the most efficient; very long flights tick back up because the plane burns extra fuel just to carry the weight of its own fuel.
Per passenger-kilometre, a full flight is similar to one person driving a petrol car and far worse than rail. This calculator shows all three for the same distance. The catch is that flights cover huge distances, so a single trip’s total is usually much larger than any drive you would realistically make.
Count what you actually fly. Most trips are round trips, so that is the default and simply doubles the distance. Switch to one-way for a single leg or an open-jaw itinerary, and set the passenger count for family or group travel — the result is always per passenger and then multiplied out.
Fly less and combine trips, choose non-stop routings, and book economy over premium cabins. For flights you cannot avoid, buy verified offsets (Gold Standard or Verra) sized to your CO₂e figure — use our Carbon Offset Calculator, and the Carbon Footprint Calculator to see flying within your whole-year total.