Flight Carbon Footprint Calculator

Enter the one-way distance in miles, pick the cabin class, choose round trip or one way, and set the number of passengers. The calculator picks the short-haul or long-haul factor for you based on that distance.

Worked example: one passenger, economy, 800 miles each way, round trip. At 800 miles the short-haul factor applies: 800 × 0.2024 = 161.92 kg CO2e per leg. Doubled for the return, the trip comes to 323.84 kg CO2e, or 0.32 metric tons. The result panel shows a haul type of short-haul, a factor of 0.2024 kg/mi, and about 15 trees as the one-year offset equivalent.

The bar chart then prices the same route in every cabin. That comparison matters more than it looks for short flights, as the section on cabin class below explains.

A single number means little until you set it beside the rest of your year. The carbon footprint calculator puts flights next to home energy, driving and waste so you can see where they rank.

Per-passenger emissions (kg CO2e) = Distance (mi) × Per-mile factor × Cabin multiplier × Legs, where Legs is 2 for a round trip and 1 for one way.

Total emissions = Per-passenger emissions × Passengers. Metric tons = kg ÷ 1,000.

Per-mile factor: 0.2024 kg/mi if the distance is under 2,300 miles, otherwise 0.1884 kg/mi. Each is the 2026 economy-class factor with radiative forcing, in kg CO2e per passenger-km, multiplied by 1.609344 km per mile. The 2,300-mile boundary matches the methodology paper's rule of treating flights under 3,700 km as short-haul.

Radiative forcing: the government's methodology recommends a multiplier of 1.7 on the CO2 part of aviation emissions as a central estimate, and publishes it as a separate set of factors. That is why the economy factors used here are about 1.69× the factors without it (0.07435 short-haul, 0.06926 long-haul). It is not applied a second time.

Cabin multiplier: Economy 1.0, Premium Economy 1.6, Business 2.9, First 4.0. These are the ratios between the 2026 long-haul factors: 0.18726, 0.33940 and 0.46814 kg per passenger-km against 0.11704 for economy. Premium seats take more floor space, so fewer people share the fuel burn.

Tree equivalent = Total metric tons ÷ 0.021, a fixed assumption of 0.021 metric tons of CO2 absorbed per tree per year.

Now take one passenger flying 5,500 miles each way in business class, round trip. That is past the 2,300-mile line, so the long-haul factor applies: 5,500 × 0.1884 = 1,036.2 kg per economy leg. Multiply by 2.9 for business and by 2 for the return, and the trip totals 6,009.96 kg CO2e, or 6.01 metric tons, about 286 trees on the tool's offset scale.

The same seat in economy on that route would be 2,072.4 kg. Premium economy would be 3,315.84 kg, and first class 8,289.6 kg.

Against the 800-mile economy round trip above, this one trip is 18.6 times the footprint. Most of that gap comes from the cabin, not the extra miles. The flight is 6.9 times longer, but the business seat adds another 2.9×. The lower long-haul rate per mile pulls the total down only slightly.

Short flights cost more per mile. A short-haul economy seat is charged about 7.4% more CO2e per mile than a long-haul one (0.2024 vs 0.1884 kg/mi). Short trips are also the ones a train, a car share or a video call can replace, so that is where switching gets you the most per mile. The eco-commute and work-from-home calculator prices that swap for regular travel.

There is a step at 2,300 miles. The band switches in one jump rather than blending, so a 2,250-mile one-way flight shows 455.4 kg while a longer 2,350-mile flight shows 442.74 kg. Close to the boundary, read the result as roughly equal rather than a real saving from flying further.

Business class on short flights is overstated. The 2026 factors give short-haul flights only an economy factor and a combined first/business factor. That combined factor is 1.5× economy (0.18863 vs 0.12576 kg per passenger-km). The calculator uses the long-haul 2.9× at every distance. An 800-mile round trip in business therefore shows 939.14 kg, while the official short-haul business factor gives about 486 kg. For premium cabins on short flights, treat the result as an upper bound.

Use the great-circle distance and do not pad it. The government's methodology adds an 8% uplift to great-circle distances to cover indirect routing, holding patterns and delays. That uplift is already inside the 2026 factors. If you add 8% again to an airport-to-airport distance, you count it twice.

Enter each connecting leg on its own. Every leg has its own take-off and climb. A connection can also move part of a long trip into the short-haul band, which carries the higher per-mile rate. Run each leg separately and add the results, rather than typing the origin-to-destination distance once.

Passengers multiply, but nothing else changes. A family of four flying 1,200 miles each way in economy, round trip, comes to 485.76 kg each and 1,943.04 kg in total, about 1.94 metric tons. Emissions per passenger stay the same however many people travel together.

The factors are averages. The methodology builds them from Civil Aviation Authority statistics for UK-registered airlines, so they do not know your aircraft type, its age, the seating layout your airline uses, or how full your flight is. A newer twin-engine widebody on a full flight will usually beat the average. An older aircraft flying half-empty will do worse.

The government also publishes a separate, higher factor for UK domestic flights (0.22928 kg CO2e per passenger-km with radiative forcing). This calculator does not use it, so very short hops may be understated.

The radiative forcing multiplier is uncertain. The methodology says plainly that the 1.7 value carries significant uncertainty, so a CO2e figure that includes it is an estimate of total warming, not a measurement.

The tree figure is a fixed rule of thumb, not a sequestration rate for any real species, site or age of tree. It is not a guide to buying offsets, which range from verified removals to weak avoidance credits.

Use this tool for trip planning and personal footprint estimates. It is not suitable for corporate greenhouse gas reporting, which needs the full factor set, distance uplift conventions and reporting boundaries.

To see how a flight compares with the rest of a household's emissions, add it to the carbon footprint calculator. The Carbon Footprint Reduction Guide then walks through ranking flights, driving and home energy by how much each cut is worth. If you plan to offset a trip, the carbon offset cost comparison calculator prices the tonnage through renewable energy credits, reforestation and direct air capture, and the tree planting carbon offset calculator replaces this page's flat tree figure with sequestration by species, age and climate.

For trips that happen every week rather than once a year, the eco-commute and work-from-home calculator is usually the bigger lever. For a sense of scale on digital emissions, the website carbon footprint calculator estimates a site's annual emissions from page weight and traffic.