Flight Carbon Calculator
Estimate the CO₂ emissions of a flight based on distance, cabin class, and number of passengers. Use it before booking to compare routes or offset options.
About this calculator
Aviation emissions are calculated per passenger using distance, a per-km emission factor, and a cabin-class multiplier that reflects the larger seat footprint of premium cabins. The formula used here is: CO₂ (kg) = distance × 0.255 × class_multiplier × passengers, where 0.255 kg CO₂/km is a standard per-passenger economy factor derived from ICAO methodology. Business class is assigned a multiplier of 2 because those seats occupy roughly twice the floor space, while first class is 3×. This approach is consistent with the UK government's greenhouse gas conversion factors for air travel. Note that this formula covers CO₂ only; aviation's total climate impact (including NOₓ and contrail effects) is estimated to be 2–4× higher.
How to use
Example: two passengers flying London to New York (5,570 km) in economy class. Step 1 — Enter distance: 5,570 km. Step 2 — Select flight class: economy (multiplier = 1). Step 3 — Enter passengers: 2. Calculation: 5,570 × 0.255 × 1 × 2 = 2,840.7 kg CO₂. That is about 2.84 tonnes of CO₂ for the pair. Had they flown business class (multiplier = 2), the result would double to 5,681.4 kg CO₂ — showing how cabin choice dramatically affects your footprint.
Frequently asked questions
Why does flying business class produce more CO₂ than economy on the same flight?
Business and first class seats are physically larger and heavier, so each passenger claims a greater share of the aircraft's total weight and fuel burn. A business class seat can occupy two to three times the floor area of an economy seat, which is why the multiplier in this calculator is 2× for business and 3× for first. On a long-haul flight, a single business class passenger can generate as much CO₂ as three economy passengers making the same journey. This is why choosing economy is consistently cited as one of the most effective individual steps to lower aviation emissions.
How accurate is a per-km emission factor for calculating flight carbon?
Per-kilometre emission factors like the 0.255 kg CO₂/km used here are averages derived from large datasets of real flights, accounting for fuel burn, load factors, and aircraft type. They are reasonably accurate for long-haul routes but can overestimate or underestimate by 20–30% for short hops, where the fuel-intensive take-off and climb phases represent a larger share of total emissions. For the most precise estimate, tools like ICAO's Carbon Emissions Calculator use specific aircraft type and routing data. This calculator provides a reliable first-order estimate suitable for personal carbon budgeting and offset purchasing.
What is the best way to offset carbon emissions from a flight?
Carbon offsetting means funding a project that removes or avoids an equivalent amount of CO₂ elsewhere — common options include reforestation, cookstove distribution, and direct air capture. To offset effectively, choose projects certified by Gold Standard or Verified Carbon Standard (VCS), as these ensure rigorous monitoring and permanence. Use this calculator to find your total kg of CO₂, then purchase that many kg of verified credits — prices typically range from $5 to $50 per tonne. Critics note that offsets are not equivalent to not flying, so reducing flight frequency remains the highest-impact action, with offsetting as a complementary measure.