Flight Emissions Tracker

Two emissions estimates for the same flight can differ without either calculation containing an arithmetic error. Distance, aircraft and load assumptions, passenger allocation, cabin class, non-CO2 effects, and sustainable aviation fuel scenarios all change what the final number represents.

A distance-based estimate starts with each route leg and assigns carbon dioxide per passenger-kilometre. Short flights often have a higher factor because takeoff and climb make up a larger share of the journey. Premium cabins can receive a larger share because each passenger occupies more aircraft space in the comparison.

Airport pairs can supply a great-circle distance, the shortest path over a spherical Earth. Actual flights may travel farther because of airways, weather, holding, diversions, and air-traffic control. A manual distance is useful when the planned or measured leg length is known, but its source and units should be recorded for a fair comparison.

Radiative forcing (RF) is especially uncertain at the individual-flight level. Contrails and other non-CO2 effects depend on altitude, location, time, weather, engine, and fuel conditions. A multiplier is a scenario choice for sensitivity analysis, not a precise observation of one journey.

Use a fixed-factor result to compare documented scenarios, not as an airline inventory or regulatory report. A flight-specific method that uses aircraft type, fuel burn, load factor, cargo allocation, and operational data can produce a materially different estimate.

How to Use This Tool:

List the itinerary one leg per line, then choose the assumptions that should stay fixed across comparisons.

1. Enter up to 12 legs as two three-letter IATA codes, such as JFK-LHR. Add a manual distance when needed, for example SFO-HND 5124 mi.
2. Choose One-way or Round trip. Round trip doubles every listed leg; do not list the return legs as well unless they are genuinely additional itinerary segments.
3. Select the Cabin class and number of Travelers. These affect the passenger allocation and trip total.
4. Choose direct CO2 or the RF scenario, then set any SAF share and documented Offset budget price.
5. Choose Calculate emissions and correct any skipped-leg warning before using the total.
6. Compare the leg audit with the method ledger to confirm every applied distance and multiplier.

Interpreting Results:

Estimated trip emissions is the total CO2e for all travelers and the selected one-way or round-trip count. The per-passenger value divides that same total by the traveler count. When RF is disabled, the effective RF multiplier is 1 and CO2e equals the direct CO2 scenario.

Use the leg audit to find the largest contributor and confirm its distance band. A longer leg can have a lower per-kilometre factor yet still dominate the trip because it covers far more kilometres. Changing cabin, SAF, RF, travelers, or trip type scales the result without changing the route distance.

• A warning about a skipped leg means the displayed total excludes that line.
• A manual distance takes precedence over the airport-coordinate lookup.
• The offset amount is a budget estimate only; it does not reduce the emissions total.
• Compare scenarios only when route, trip type, traveler count, and all model choices are held consistently.

Technical Details:

This is a repo-authored fixed-factor comparison model. It uses distance bands and explicit multipliers rather than reproducing the operational ICAO Carbon Emissions Calculator or IATA passenger methodology.

Formula Core

For leg i, direct carbon dioxide per passenger multiplies distance d, haul factor f, cabin multiplier c, and the sustainable aviation fuel multiplier derived from SAF share s.

The trip total multiplies each per-passenger result by effective RF multiplier r, passenger count p, and trip multiplier t, then sums every leg.

RF is the selected 1.00 to 3.00 multiplier when enabled and 1 otherwise. Trip multiplier is 1 for one-way and 2 for round trip. An offset price q in USD per tonne gives a budget of (E_trip/1000) × q.

Rule Core

The SAF multiplier is 1 − 0.7 × share/100. It is 1.00 at 0% SAF and 0.30 at 100% SAF, reflecting the model's fixed 70% lifecycle-saving assumption for the selected share.

Lookup Core

A line without a manual distance uses latitude and longitude from the public airport registry. The great-circle calculation applies the haversine formula with an Earth radius of 6,371 km. A distance entered in miles is multiplied by 1.60934; a number without a unit is treated as kilometres.

Every resolved distance must be greater than 0 and no more than 25,000 km. Travelers must be a whole number from 1 to 1,000, SAF share from 0% to 100%, and offset price from 0 to 10,000 USD per tonne of CO2e.

For the sample 5,540 km JFK-LHR leg in economy with no SAF, RF 1.9, one traveler, and round trip, direct CO2 is 637.1 kg per direction. CO2e is 1,210.49 kg per direction and 2,420.98 kg for the counted round trip across 11,080 km.

The calculation keeps full floating-point precision. Displayed masses use one decimal place, distances use no decimal places, factors use three decimal places, and currency uses two; display rounding does not feed back into later calculations.

Accuracy Notes:

The result is an educational comparison estimate, not measured emissions, an airline inventory, a carbon-accounting certificate, or proof of an offset or SAF claim.

• Fixed distance factors do not use the actual aircraft, fuel burn, load factor, cargo allocation, route flown, or airline operations.
• Great-circle distance is normally shorter than the flown track, while manual distance is only as reliable as its source.
• The RF multiplier represents uncertain non-CO2 effects and should be reported with the chosen value.
• The fixed SAF saving does not model feedstock, production pathway, chain of custody, availability, or claim ownership.
• Airport-only routes download a public registry after calculation is requested and resolve codes in the browser. Manual-distance routes do not need that lookup.
• The airport registry can contain missing, duplicate, or outdated codes and coordinates; inspect every resolved leg before using the total.

References:

• ICAO Carbon Emissions Calculator, International Civil Aviation Organization.
• ICAO Carbon Emissions Calculator Methodology, Version 13.1, International Civil Aviation Organization, August 2024.
• Passenger CO2 Standard Methodology, International Air Transport Association.
• Non-CO2 Emissions and Effects, International Air Transport Association.
• Airports JSON Registry, mwgg/Airports.