What is the great-circle distance between airports?

The shortest path between two points on a sphere is called a great-circle distance. Because the Earth is roughly spherical, aircraft follow great-circle routes rather than straight lines on a flat map — this is why transatlantic flights curve far north over Greenland instead of heading due west. The distance between any two airports is therefore calculated along the surface of a sphere, not as a straight Euclidean line.

The standard formula for this calculation is the Haversine formula, which uses the latitude and longitude of each location and the mean radius of the Earth (6,371 km) to produce an accurate result within about 0.5 % of the true geodesic distance.

Tool description

Airport Distance Calculator lets you select any two airports worldwide and instantly see the great-circle distance between them. Pick a departure airport and an arrival airport from searchable dropdowns — results update automatically and are displayed on an interactive map alongside numeric results in three unit systems and an estimated flight time.

Features

  • Searchable dropdowns covering all large and medium IATA-coded airports worldwide
  • Distance shown simultaneously in kilometres, miles, and nautical miles
  • Estimated flight time based on a typical commercial cruise speed of 900 km/h
  • Interactive route map rendered with Leaflet, showing both airport markers and the connecting great-circle path
  • Zero configuration — no API keys or sign-up required

How it works

  1. Select the Departure airport and the Arrival airport from the searchable dropdowns.
  2. The tool fetches the latitude and longitude for each IATA code from the bundled airport-data-js dataset.
  3. The Haversine formula computes the great-circle distance between the two coordinate pairs.
  4. Results are converted to miles (× 0.621371) and nautical miles (× 0.539957).
  5. Estimated flight time is calculated by dividing the distance in km by 900 km/h (a common cruising speed for commercial jets).
  6. A Leaflet map renders markers at each airport and draws the route line between them.

Use cases

  • Trip planning: Quickly compare the distances for different routing options before booking flights.
  • Aviation education: Visualise how great-circle routes differ from the straight lines drawn on flat maps.
  • Logistics and freight: Estimate air-freight distances for cost calculations or lead-time estimates.

Limitations

  • Only large and medium airports with valid IATA codes are included; small private airfields and heliports are not listed.
  • Flight time is a rough estimate based on a fixed 900 km/h cruise speed and does not account for winds, routing detours, or climb/descent phases.
  • The route line drawn on the map is a straight line between the two coordinate pairs rather than a true curved great-circle arc on the 2-D projection.

FAQ

Why is the distance different from what my airline shows? Airlines file flight plans that follow air-traffic control corridors, avoid restricted airspace, and account for wind patterns — the actual flown distance is almost always longer than the theoretical great-circle distance shown here.

What does "nm" mean? "nm" stands for nautical miles, the standard unit of distance used in aviation and maritime navigation. One nautical mile equals exactly 1.852 kilometres.

Is the cruise speed of 900 km/h accurate? It is a reasonable average for typical commercial jets (roughly Mach 0.82–0.85 at cruise altitude). Narrowbody aircraft tend to fly slightly slower (850 km/h) and some widebodies slightly faster (920 km/h). Use the estimate as a rough guide only.