How Much CO2 Does a Flight Emit? (And How to Offset It)
A single passenger's flight typically emits about 0.2–0.5 tonnes of CO₂ on a short-haul return and roughly 1–2 tonnes on a long-haul return like London–New York in economy. Those are useful ballpark figures, but the real number depends on distance, cabin class, how full the plane is, and a high-altitude warming effect that most calculators leave out. Real per-passenger figures Short-haul return (say London–Rome or a domestic hop) lands around 0.2–0.5 t CO₂ per economy seat. Medium-haul return (London–Cairo, roughly 4,000 km each way) sits near 0.7–1 t. Long-haul return like London–New York is about 1–2 t per economy passenger; London–Singapore or Sydney can reach 3–4 t. Cabin class multiplies it — business seats take 2–3× the space and emissions of economy, and first class 3–4×, because the footprint is shared across fewer people. Load factor matters — a half-empty plane spreads its fuel burn across fewer passengers, pushing per-head emissions up. Putting a flight in perspective The reason flying dominates so many personal footprints is that a single decision produces emissions comparable to months of everything else. A long-haul return in economy is roughly on the order of an average person's annual footprint in several lower-emitting countries, and it can exceed a year of home electricity in a grid with plenty of renewables. That is not an argument for guilt; it is an argument for spending your attention where the tonnes are. Fine-tuning standby power while flying four times a year is optimising the wrong variable — the ranking is set out in how to reduce your carbon footprint. The high-altitude effect most calculators miss Burning jet fuel does not only release CO₂. At cruising altitude, aircraft also produce contrails, water vapour and nitrogen oxides that trap extra heat — a phenomenon called radiative forcing. Peer-reviewed estimates suggest this roughly doubles a flight's total warming impact compared with the CO₂ figure alone. So a long-haul return that shows as 1.5 t of CO₂ may be closer to 3 t in real climate terms. When you work out your own flights with the free Evertreen CO₂ calculator, treat the CO₂-only output as a floor, not a ceiling. Worth knowing: contrail warming is short-lived compared with CO₂, which persists for centuries, so the two are not identical in kind. That is a reason to report both rather than to ignore the one that is harder to model. What does and doesn't reduce a flight's emissions Fly direct. Take-off and climb burn a disproportionate share of the fuel, so two short legs usually beat one longer one only in the wrong direction — a single non-stop is generally lower. Fly economy. The biggest single per-passenger variable you actually control on a given route. Choose newer aircraft where you can. Fleet age makes a measurable difference to fuel burn per seat. Pack lighter. Real, but small — worth doing, not worth agonising over. Sustainable aviation fuel is genuinely lower-carbon over its life cycle, but supply is tiny and most "SAF-inclusive" tickets buy a small blended share. Read the fine print before treating it as a solution. Carbon-neutral ticket badges vary enormously in quality. Ask which standard, which project and whether retirement happens in your name. The uncomfortable summary: the only large lever is flying less. Everything else trims a percentage off a number that is already big. How to cut it — then offset the rest The biggest lever is simply flying less: one avoided long-haul trip saves more than a year of most other lifestyle tweaks combined. When you do fly, choose direct routes, pick economy over business, pack lighter, and favour newer aircraft where you can. For the emissions you cannot avoid, offsetting with real, verifiable projects closes the gap. Evertreen's geolocated trees come with a GPS pin and progress photos so you can see exactly what your money planted, and you can start from just £1.5 per tree. Be clear-eyed about the timing, though: a flight's emissions happen this week, while a tree absorbs carbon over decades. Planting is a genuine long-term removal contribution rather than a same-day cancellation — the arithmetic is in how many trees to offset your carbon footprint. Choosing a credible offset Offsetting only works if the carbon is genuinely additional and independently checked, which is why quality standards matter. Evertreen offers certified Verra and Gold Standard carbon credits on request for the residual tonnes a flight leaves behind — the same registries used by serious corporate buyers. Pairing traceable trees for a visible, long-term impact with certified credits for measured, retirable tonnes gives you an honest response to air travel: reduce first, then offset what is left with something you can actually verify. If you are comparing standards, see Verra vs Gold Standard. Frequently asked questions How much CO₂ does a return flight from London to New York emit? Roughly 1–2 tonnes of CO₂ per economy passenger, or closer to 3 tonnes once the high-altitude warming effect is included. Business or first class can multiply that by 2–4 times. Does economy really emit less than business class? Yes — a business seat occupies 2–3 times the floor space of economy and first class up to 4 times, so the same flight's fuel is shared across fewer people, raising the per-passenger footprint proportionally. How many trees offset one long-haul flight? As a rough guide, a mature tree absorbs around 20–25 kg of CO₂ per year, so offsetting 2 tonnes takes a modest grove planted over time; certified credits retire the tonnes immediately if you need proof for a given year. Is flying worse than driving? Per kilometre, flying is usually worse than a car carrying several people, and much worse than rail. Over the same journey, distance and occupancy decide it — but flights tend to cover distances nobody would drive. Do direct flights emit less than connecting ones? Generally yes, because each take-off and climb is fuel-intensive and connections often add total distance flown. Does sustainable aviation fuel solve this? Not yet. It lowers life-cycle emissions but supply is very limited, and most tickets marketed with it include only a small blended share. Should I offset my flights? Offsetting a flight you could not avoid is a reasonable contribution, provided the credits are certified and retired in your name. It is not a substitute for taking fewer flights. { "@context": "https://schema.org", "@type": "FAQPage", "mainEntity": [ {"@type": "Question", "name": "How much CO2 does a return flight from London to New York emit?", "acceptedAnswer": {"@type": "Answer", "text": "Roughly 1 to 2 tonnes of CO2 per economy passenger, or closer to 3 tonnes once the high-altitude warming effect is included. Business or first class can multiply that by 2 to 4 times."}}, {"@type": "Question", "name": "Does economy really emit less than business class?", "acceptedAnswer": {"@type": "Answer", "text": "Yes. A business seat occupies 2 to 3 times the floor space of economy and first class up to 4 times, so the same fuel is shared across fewer passengers."}}, {"@type": "Question", "name": "How many trees offset one long-haul flight?", "acceptedAnswer": {"@type": "Answer", "text": "A mature tree absorbs around 20 to 25 kg of CO2 per year, so offsetting 2 tonnes takes a modest grove over time. Certified credits retire the tonnes immediately if proof is needed for a given year."}}, {"@type": "Question", "name": "Is flying worse than driving?", "acceptedAnswer": {"@type": "Answer", "text": "Per kilometre, flying is usually worse than a well-occupied car and much worse than rail. Over a given journey, distance and occupancy decide it, though flights cover distances nobody would drive."}}, {"@type": "Question", "name": "Do direct flights emit less than connecting flights?", "acceptedAnswer": {"@type": "Answer", "text": "Generally yes, because each take-off and climb is fuel-intensive and connections often add total distance flown."}}, {"@type": "Question", "name": "Does sustainable aviation fuel solve aviation emissions?", "acceptedAnswer": {"@type": "Answer", "text": "Not yet. It lowers life-cycle emissions but supply is very limited and most tickets marketed with it include only a small blended share."}}, {"@type": "Question", "name": "Should I offset my flights?", "acceptedAnswer": {"@type": "Answer", "text": "Offsetting an unavoidable flight is a reasonable contribution if the credits are certified and retired in your name, but it is not a substitute for flying less."}} ] }