Flight Carbon Footprint Calculator
Why Calculate Flight Carbon Emissions?
Air travel is one of the fastest-growing sources of greenhouse gas emissions. A single long-haul, round-trip flight can produce more carbon dioxide (CO₂) per passenger than many people generate from months of driving. Estimating the footprint of each journey helps you:
- See the climate impact of a specific trip alongside the ticket price.
- Compare different routes or modes of travel.
- Plan how much to reduce or offset your annual flying.
This calculator gives you a simple estimate of CO₂ emissions based on the coordinates of your departure and arrival airports and the number of passengers you are booking for.
How Distance Between Airports Is Calculated
Airplanes typically follow a great-circle route, which is the shortest path between two points on a sphere. To approximate that distance, the calculator uses the haversine formula, a standard method in navigation and geodesy.
You provide the latitude and longitude for your origin and destination airports. The formula then converts the difference in coordinates into an angular distance on Earth, and multiplies by Earth’s average radius to get a straight-line flight distance.
Haversine Distance Formula
Let:
- R = Earth’s mean radius (about 6,371 km or 3,959 miles)
- φ₁, φ₂ = latitudes of origin and destination (in radians)
- λ₁, λ₂ = longitudes of origin and destination (in radians)
The haversine formula is:
where Δφ = φ₂ − φ₁ and Δλ = λ₂ − λ₁. The result d is the great-circle distance between the two airports.
From Distance to CO₂ Emissions
Once the distance is known, the calculator multiplies it by an average emissions factor to estimate CO₂ per passenger. A typical assumption for commercial flights (including an allowance for high-altitude effects) is:
- Emissions factor: about 0.2 kg CO₂ per passenger-mile
The basic relationship is:
CO₂ per passenger = Distance × Emissions factor
If the distance is in miles and the factor is 0.2 kg CO₂ per passenger-mile, then a 1,000 mile flight creates roughly 200 kg of CO₂ for one traveler.
Per-Passenger vs Total Flight Emissions
By default, the calculation is per passenger. The calculator then multiplies this by the number of travelers you enter to show a combined footprint:
Total CO₂ = CO₂ per passenger × Number of passengers
This is useful if you are booking for a family, a group holiday, or a business trip and want to understand the total impact of all tickets you are buying.
Remember that in reality, the plane’s total emissions are shared across every seat on the aircraft. Flying together on a full plane is generally more efficient per person than flying on a half-empty aircraft or taking multiple separate flights.
Worked Example
Suppose you fly from a departure airport at (40.6° N, 73.8° W) to a destination at (51.5° N, 0.0° W). These are approximate coordinates for New York (JFK area) and London (Heathrow area).
- Convert coordinates to radians and apply the haversine formula to get the distance. The great-circle distance between these points is about 3,450 miles (5,550 km).
- Estimate per-passenger CO₂ using 0.2 kg CO₂ per passenger-mile:
3,450 miles × 0.2 kg CO₂ / mile ≈ 690 kg CO₂ per passenger. - Estimate for multiple passengers. If you enter 2 passengers:
690 kg × 2 ≈ 1,380 kg CO₂ (about 1.38 metric tons) for both travelers.
Your actual airline and aircraft may differ, but this gives a reasonable order-of-magnitude estimate for planning and comparison.
Interpreting Your Results
The calculator will show:
- Estimated distance between the two airports.
- CO₂ emissions per passenger for the one-way flight.
- Total CO₂ emissions for all passengers you entered.
You can use these numbers to:
- Compare different routes (e.g., direct vs. connecting flights).
- Decide whether a trip is worth its climate cost.
- Estimate the impact of your annual business or leisure travel.
For context, many passenger cars emit roughly 4–5 metric tons of CO₂ per year. A single long-haul round-trip flight in economy can therefore represent a significant portion of a person’s yearly footprint.
Quick Comparison of Example Flights
| Flight type | Approx. distance (one way) | CO₂ per passenger (one way) | Notes |
|---|---|---|---|
| Short domestic hop | 500 miles | ≈ 100 kg CO₂ | Similar to driving a typical car for several hundred miles. |
| Cross-country flight | 3,000 miles | ≈ 600 kg CO₂ | Roughly a significant slice of one person’s annual car emissions. |
| Intercontinental long haul | 8,000 miles | ≈ 1,600 kg CO₂ | Over 1.5 metric tons of CO₂ for a single passenger one way. |
How to Use the Calculator Effectively
- Enter airport coordinates: Use the latitude and longitude of your departure and arrival airports, not your street address. You can usually find these by searching for “[airport name] latitude longitude” in a map or search service.
- Decide one-way vs round trip: The distance is for one-way travel. For a round trip, you can mentally double the result or run the calculation twice.
- Adjust passenger count: Increase the passenger number to see the combined footprint of your group.
- Compare options: Try different airport pairs or route options to see how distance and emissions change.
Limitations and Assumptions
This tool is designed to give a simplified estimate, not an exact value. Key assumptions and limitations include:
- Straight great-circle path: Real flights may be longer due to air traffic control, weather deviations, holding patterns, or detours. The calculator does not add extra distance for these factors.
- Average emissions factor: The 0.2 kg CO₂ per passenger-mile figure is a broad average. Actual emissions vary with aircraft type, airline, seating layout, load factor, and engine technology.
- Class of travel: The calculation assumes economy-style seating. Premium cabins take more space per passenger and can therefore correspond to higher per-person emissions than this simple average suggests.
- One-way basis: Results are for a single leg. To approximate a round trip, multiply the emissions by two.
- Non-CO₂ effects: The factor used here attempts to partially reflect additional warming from high-altitude effects (such as contrails and ozone formation), but these processes are complex and uncertain. Different studies may use higher or lower multipliers.
- Layovers and connections: If you take connecting flights, the total distance (and emissions) may be higher than a nonstop route between the same endpoints. To approximate this, you can run the calculator separately for each leg and add the results.
Because of these limitations, treat the output as a best-effort estimate for comparison and planning, not a precise engineering calculation.
About Offsetting Flight Emissions
You may see suggestions to “offset” your flight emissions through climate-related projects. In practice, high-quality offsets usually come from independently verified initiatives such as reforestation, conservation, or clean energy projects that are certified by third-party standards.
Offsets can be a useful complement to direct reductions, but they are not a substitute for flying less, choosing more efficient routes, or favoring less carbon-intensive modes of transport where practical. Use this calculator to understand your impact first, then decide which combination of reduction and offsetting best fits your goals.