Convert CO₂e to Flights (London–New York)
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One of the most relatable ways to picture a CO₂e figure is as return transatlantic flights. This converter uses DEFRA’s aviation factors: a return London–New York economy flight emits about 1.30 tonnes of CO₂e per passenger, including radiative forcing (aviation’s non-CO₂ warming), so a CO₂e total divided by 1.30 gives the equivalent number of return flights — roughly 0.77 flights per tonne. The factor is read live from the GreenCalculus MasterBrain and cited to DEFRA. It is a communication device for putting a number in perspective, not a carbon-accounting method.
Divide the CO₂e in tonnes by 1.2968 — the tonnes of CO₂e for one return economy London–New York flight with radiative forcing (DEFRA). So 1 t CO₂e ≈ 0.77 return flights, and one return flight is about 1.30 t.
return flights = tonnes CO₂e ÷ 1.2968 (≈ × 0.771). Reverse: tonnes CO₂e = return flights × 1.2968. The 1.2968 t is one return London–New York economy flight per passenger, with radiative forcing; the converter reads it live from the MasterBrain, so it updates if DEFRA revises the factors.
| CO₂e | × 0.771 | Return LON–NYC flights |
|---|---|---|
| 1.30 t CO₂e | — | 1 return flight |
| 1 t CO₂e | × 0.771 | 0.77 return flights |
| 5 t CO₂e | × 0.771 | 3.9 return flights |
| 10 t CO₂e | × 0.771 | 7.7 return flights |
How the equivalency works
There is no single official “London–New York flight” number, so this figure is built from the UK Government (DEFRA) greenhouse-gas conversion factors for air travel, applied to the route distance.
Where 1.30 tonnes comes from
DEFRA publishes a per-passenger-kilometre factor for long-haul flights to or from the UK. For economy class, with radiative forcing, it is 0.11704 kg CO₂e per passenger-km. The great-circle distance from London to New York is about 5,540 km; DEFRA’s factors already include an 8% uplift for indirect routing and holding, so they apply to the great-circle distance, and a return trip doubles it — so 5,540 × 2 = 11,080 km. Multiplying gives ≈ 1.30 tonnes of CO₂e per passenger for the return economy flight.
1.2968 tonnes CO₂e per return London–New York economy flight, per passenger, including radiative forcing (DEFRA 2026 long-haul economy, 0.11704 kg CO₂e/passenger-km × 11,080 km). Basis is AR5 CO₂e with radiative forcing; it excludes the well-to-tank emissions of producing the jet fuel (a further ~21%).
The four common bases
Flight figures vary a lot depending on two choices: one-way or return, and whether radiative forcing is included. All four are economy class, per passenger:
| Basis | One-way | Return |
|---|---|---|
| With radiative forcing (this converter) | 0.65 t CO₂e | 1.30 t CO₂e |
| Without radiative forcing | 0.38 t CO₂e | 0.77 t CO₂e |
The converter uses the return, with-radiative-forcing figure — the most complete climate impact for the trip most people mean by “a flight to New York.” Without radiative forcing the return is 0.77 t; that figure leaves out the non-CO₂ warming below.
CO₂e to flights conversion table
To reverse any row, multiply the number of return flights by 1.2968 tonnes.
| t CO₂e | Return LON–NYC flights (× 0.771) |
|---|---|
| 0.5 | 0.39 |
| 1 | 0.77 |
| 1.30 | 1.00 |
| 5 | 3.9 |
| 10 | 7.7 |
| 100 | 77.1 |
What “flights” does and doesn’t mean
A flight is a vivid unit — and one where the basis really matters. Four caveats keep the comparison honest.
It’s a return flight, per passenger
The unit is one return economy flight for one passenger. A one-way flight is half (about 0.65 t), and it is per seat, not per plane — a full aircraft’s total is this figure times a few hundred. Say “return flights per passenger” when you present it.
It includes radiative forcing
Burning fuel at altitude does more than release CO₂: contrails and nitrogen-oxide effects add warming on top of the CO₂. DEFRA approximates this by adding 70% to the flight’s CO₂, and this converter includes it, because for aviation the non-CO₂ effects are large and well established. Drop it and the same return flight is 0.77 t instead of 1.30 t. Whichever you use, state it.
It’s economy class
A premium seat takes more of the plane’s floor space, so it carries more of the emissions. On DEFRA’s factors a business-class long-haul seat is roughly 2.9× economy and first class about 4×. The converter uses economy as the typical traveller; scale up for premium cabins.
It’s for communication, not accounting
An equivalency is a way to describe a CO₂e figure, not a way to calculate one. Never enter “flights” into a greenhouse-gas inventory as if it were an activity — for an actual flight, use the business travel (air) calculator with the real route and class (Scope 3, Category 6). Use this converter to make a number relatable in a report or presentation, and cite the DEFRA basis.
Where the conversion is used
- Reporting and communication. Making a footprint or a target tangible — “our travel emissions this year are about 300 return New York flights.”
- Context for a travel footprint. Estimate the real thing with the business travel (air) calculator, then express the total in flights everyone pictures.
- Alongside other equivalencies. Flights are one of many relatable units; the CO₂ equivalencies calculator converts a figure into cars, trees, gallons and more at once (method: the CO₂ equivalencies methodology). See also the cars-driven-per-year, gallons-of-gasoline, tree-seedlings and smartphones-charged converters, and the other emissions unit converters.
Enter the CO₂e in tonnes, not kilograms — the factor is tonnes per flight. If your figure is in kilograms, divide by 1,000 first. And name the basis: “≈ N return London–New York economy flights (DEFRA, incl. radiative forcing)” tells the reader exactly what the comparison rests on.
Frequently Asked Questions
Divide the CO₂e (in tonnes) by 1.2968, the tonnes of CO₂e for one return economy flight with radiative forcing — the same as multiplying by about 0.771. For example, 5 tonnes CO₂e ≈ 3.9 return flights. To reverse it, multiply the number of flights by 1.2968.
About 0.77 of a return economy flight (1 ÷ 1.2968), or about 1.5 one-way flights. Put the other way, one return London–New York flight accounts for roughly 1.30 tonnes of CO₂e per passenger, including radiative forcing.
About 1.30 tonnes of CO₂e per passenger in economy, including radiative forcing (DEFRA). Without radiative forcing it is about 0.77 tonnes. Business class is roughly 2.9× and first class about 4× the economy figure. The carbon footprint of flying guide compares other routes.
Yes. Aviation warms the climate through more than CO₂ — contrails and nitrogen-oxide effects at altitude add more. DEFRA approximates this by adding 70% to the flight’s CO₂, and this converter includes it because those effects are large and well established for flights. Without it, the return would be about 0.77 t.
Return — there and back, which is what “a flight to New York” usually means. A one-way flight is half: about 0.65 tonnes of CO₂e in economy with radiative forcing.
A lot. A premium seat uses more of the aircraft’s floor area, so it carries more emissions. On DEFRA’s factors a long-haul business seat is roughly 2.9× economy and first class about 4×. This converter uses economy as the typical traveller; scale up for premium cabins.
Per passenger. The figure is one economy seat on the flight. A whole aircraft’s emissions are this number multiplied by the few hundred passengers on board.
No — an equivalency describes a CO₂e figure, it doesn’t calculate one. For a real flight in an inventory, use the business travel (air) calculator with the actual route and class (Scope 3, Category 6). Use this converter to make a number relatable in a report or presentation.