Flight Carbon Footprint Calculator
Work out what a flight actually emits, by distance and by the seat you are sitting in
The flight
Great-circle distance between the two airports.
Mid-range for a reforestation credit. Durable removals cost far more.
This flight
Same flight, different cabin
Same journey, different mode
Where the trip is physically possible by land. Ground figures exclude radiative forcing, which does not apply at ground level.
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How this is worked out
The distance you fly is multiplied by an emission factor per passenger-mile, then by a factor for the seat you occupy, then by a multiplier for the extra warming caused by emitting at altitude.
The per-passenger-mile factors come from EPA and vary by haul band, which produces a result that surprises people: medium-haul flights are the most efficient per mile. Takeoff and climb burn a disproportionate share of the fuel, so a very short hop spreads that over few miles; a very long flight has to carry the weight of its own fuel across an ocean. The 300 to 2,300 mile band sits in the sweet spot between the two.
About the cabin multipliers
Emissions are allocated by the floor area a seat takes up, because that is what sets how many people the aircraft carries. Defra's published seat-area ratios for long haul are economy 1, premium economy 1.6, business 2.9 and first 4.0.
EPA's factors are published per average passenger, so those ratios have to be normalised against a seat mix to be used alongside them. This calculator assumes 80% economy, 10% premium economy, 8% business and 2% first on long haul, and 90% economy to 10% business on shorter routes. Selecting "Average (all cabins)" bypasses that assumption entirely and gives you EPA's published figure unmodified.
Where the numbers come from
- Flight emissions: EPA GHG Emission Factors Hub 2025, Table 10 — 0.207 kg CO2 per passenger-mile under 300 miles, 0.129 for 300–2,300, 0.163 above. Combustion only. EPA sources these from Defra's 2022 factors and has deliberately held them at that release, because later ones reflect COVID-depressed load factors.
- Radiative forcing: 1.9x, the Defra convention.
- Routing uplift: 8% above great-circle distance, also Defra, covering indirect routing, stacking and taxiing.
- Cabin ratios: Defra seat-area weightings, normalised as described above.
- Tree equivalent: EPA Greenhouse Gas Equivalencies — 0.060 metric tons CO2 per urban tree seedling per year, averaged over ten years.
How to Use This Calculator
- Pick a route or enter a distance. Choose one of the common routes to load its great-circle distance, or type the one-way distance for any other flight. Search for your airport pair plus "great circle distance" if you need the number.
- Choose one way or return. A return trip is exactly twice a one way. Most people underestimate a holiday by forgetting the flight home.
- Select your cabin. Emissions are allocated by the floor area a seat occupies, so this matters more than people expect. A long-haul business seat carries about three times an economy seat's share of the same aircraft.
- Decide on radiative forcing. Left on by default. It accounts for contrails and high-altitude nitrogen oxide chemistry, which roughly double the warming effect of the CO2 alone. Turning it off gives the fuel-burn figure only.
- Compare and consider offsetting. The result is shown against the same journey by rail, bus and car, and against every other cabin on your route. The offset cost uses a mid-range voluntary market price, which you can change.
Frequently Asked Questions
How much CO2 does one flight produce?
A round trip from New York to Los Angeles in economy comes to about 1.3 tonnes of CO2 equivalent per passenger once high-altitude effects are counted - roughly a tenth of the average American's entire annual footprint, from two days of travel. A short domestic hop like Atlanta to New York is nearer 0.4 tonnes return, and New York to London in economy is around 1.9 tonnes.
What is radiative forcing and should I include it?
Aircraft emit at altitude, where contrails and nitrogen oxide chemistry cause warming beyond the CO2 itself. The UK's Defra applies a 1.9 times multiplier to account for it, and that is the standard convention for disclosure. Excluding it understates aviation's climate impact by nearly half, so this calculator includes it by default. The exact multiplier is still an active area of research, which is why there is a toggle.
Why does business class emit almost three times as much as economy?
Because emissions are allocated by the floor area each seat occupies, which is what determines how many passengers the aircraft can carry. Defra's weighting gives a long-haul business seat about 2.9 times the area of an economy seat, premium economy 1.6 times, and first class 4.0 times. Flying business on a long-haul route roughly triples your share of the same flight's fuel burn, for exactly the same journey.
Why do short flights emit more per mile than long ones?
Takeoff and climb burn a disproportionate share of a flight's fuel, and on a short hop that fixed cost is spread over very few miles. EPA's factors are 0.207 kg CO2 per passenger-mile under 300 miles against 0.129 for 300 to 2,300 miles. Very long flights tick back up to 0.163 because the aircraft has to carry the weight of its own fuel across an ocean.
Is buying an offset the same as not flying?
No. An offset at typical market prices buys avoided or removed carbon somewhere else, but avoidance credits such as forest protection depend on a counterfactual that is hard to verify, and durable removals that genuinely reverse the emission cost ten to forty times more - biochar averages around $177 a tonne and direct air capture over $500. Flying less, flying economy and flying direct all reduce emissions with no verification risk at all.