For most travellers, flying is the single biggest part of their carbon footprint. Enter your route and cabin class and the free, expert-backed Sustrax flight calculator shows the emissions of your trip in seconds, so you can compare options, plan reductions and offset what remains.
Choose your departure and arrival airports, cabin class and whether you are flying one way or return. Add as many legs as your journey needs and the calculator totals the emissions as you go.
A single long-haul return flight can produce more carbon than months of everyday commuting, home energy use and food combined. Knowing the number is the first step: it lets you weigh a direct flight against a connection, economy against business class, or a flight against the train.
The calculator is built and maintained by the Carbon Footprint Ltd team, using the same expert-backed emission factors that underpin our professional carbon assessments for airlines, airports and corporate travel programmes.
A flight footprint is most useful when it leads somewhere. Plan the whole trip, report it for your business, balance what you cannot avoid, or give your own visitors the same tool.
Flights are only part of the picture. The Holiday Carbon Calculator walks you through transfers, accommodation and spending on food and activities, step by step.
Try the holiday calculator Business TravelLog business flights alongside energy, vehicles and public transport in Sustrax Lite, free for a single site, or scale up to Sustrax MX for team-wide travel reporting.
Explore the business calculator Take ActionOnce you know your flight footprint, compensate for it by supporting high-impact, verified carbon projects through our Carbon Marketplace.
Visit the Marketplace For Your WebsiteTravel companies, airports, universities and charities can add the flight calculator to their own website with a ready-to-copy embed code. It is free, responsive and resizes automatically.
Get the embed codeA one-way economy flight from London to New York produces around 780 kg of CO2e per passenger, and a return trip around 1.6 tonnes. The same return trip in business class produces almost three times as much. Distance and cabin class are the two biggest factors in any flight's footprint.
The examples below were calculated with the same Sustrax emission factors used by the calculator above. Figures are kg CO2e per passenger, rounded to the nearest 10 kg, and include the upstream emissions from producing and delivering the fuel, as the calculator does. UK domestic flights are calculated for an average passenger, so no cabin class split applies. Use the calculator for your exact route.
| Route from London Heathrow | Distance | Economy, one way | Economy, return | Business, return |
|---|---|---|---|---|
| Edinburgh (domestic) | 530 km | 140 kg | 280 kg | Not applicable |
| Barcelona (short haul) | 1,150 km | 170 kg | 340 kg | 510 kg |
| New York JFK (long haul) | 5,540 km | 780 kg | 1,570 kg | 4,550 kg |
| Sydney via Singapore (long haul, one stop) | 17,180 km | 2,330 kg | 4,670 kg | 13,530 kg |
You cannot always avoid flying, but how you travel makes a big difference to the footprint of the same journey.
Travelling from London to Edinburgh by train produces around 25 kg CO2e per passenger, compared with around 140 kg for the flight. That is less than a fifth of the emissions for the same journey.
On long-haul routes a business class seat carries almost three times the footprint of economy, because it takes up more cabin space and so carries a larger share of the flight's emissions. On short-haul routes the gap is around one and a half times.
A connection usually adds extra distance and an extra take-off and landing. The calculator works out each leg separately, so add your stopovers to compare a connecting route with a direct one.
It depends mainly on distance and cabin class. As a guide, a one-way economy flight from London produces around 140 kg CO2e per passenger to Edinburgh, 170 kg to Barcelona, 780 kg to New York and more than 2.3 tonnes to Sydney. Business class on long-haul routes is close to three times higher. Enter your route in the calculator above for your exact figure.
In the UK and much of Europe, rail is usually far lower carbon than flying. Travelling from London to Edinburgh by train produces around 25 kg CO2e per passenger, compared with around 140 kg by air, which is less than a fifth of the emissions.
A flight's emissions are shared between the passengers on board. Business and first class seats take up more cabin space, so each one is allocated a larger share. On long-haul routes a business class seat carries almost three times the footprint of an economy seat.
Generally, yes. A connection usually adds distance and an extra take-off and landing, which are among the most fuel-intensive parts of a flight. The calculator works out each leg of your journey separately, so you can compare a direct route with a connecting one.
It calculates the distance between your departure and arrival airports, adds a standard uplift to reflect real-world routing, and works out the haul type from that distance. It then applies an emission factor per passenger kilometre for that haul type and cabin class, and doubles the result for a return journey.
CO2e, or carbon dioxide equivalent, expresses the warming effect of all greenhouse gases as the amount of CO2 that would have the same impact. It gives a single figure you can compare across flights, trains, cars and other activities.
You can take responsibility for emissions you cannot avoid by supporting verified carbon projects. Each carbon credit represents one tonne of CO2e reduced or removed by a project, independently verified and retired on a public registry. Offsetting does not undo the flight itself, so the best approach is to reduce first, for example by flying less, choosing economy or taking the train, and then offset what remains. Learn how carbon credits work.
Copy the free Sustrax flight calculator embed code and paste it into your own page. The holiday, personal and business calculators are available from the same page.