What is a great-circle distance?

When an aircraft flies between two airports, it doesn't follow a straight line on a flat map — it follows the shortest path along the surface of the Earth, called a great-circle route. Because the Earth is a sphere, this curved path often looks arched on a standard map projection. The distance along this path is called the great-circle distance.

Great-circle distances are calculated using the Haversine formula, which accounts for the Earth's curvature by comparing the angular separation between two latitude/longitude points. For flights, this is the standard measure of distance because it directly determines fuel consumption, flight time, and aircraft range.

Tool description

This tool lets you plan a multi-city flight route by entering a sequence of airport codes. It resolves each code to its geographic coordinates, draws arcs between consecutive airports on an interactive map, and calculates the great-circle distance for each leg individually as well as the total route distance.

Codes can be entered as IATA (3-letter, e.g. LHR) or ICAO (4-letter, e.g. EGLL) and can be mixed freely in the same route. Distances are shown in kilometers, miles, and nautical miles.

Examples

Round trip: Singapore → Chennai → Delhi → London

Input: SIN-MAA-DEL-LHR

Leg From To Distance
1 SIN — Singapore Changi MAA — Chennai International 2,887 km
2 MAA — Chennai International DEL — Indira Gandhi International 1,755 km
3 DEL — Indira Gandhi International LHR — London Heathrow 6,732 km
Total 11,417 km

Mixed IATA/ICAO codes: New York → Dubai → Sydney

Input: KJFK-OMDB-YSSY

Leg From To Distance
1 KJFK — JFK New York OMDB — Dubai International 11,013 km
2 OMDB — Dubai International YSSY — Sydney Airport 12,073 km
Total 23,046 km

Features

  • Accepts up to 20 airports per route separated by hyphens, commas, or spaces
  • Supports IATA (3-letter) and ICAO (4-letter) codes, freely mixed in the same input
  • Draws great-circle arcs on an interactive Leaflet map with airport markers
  • Shows per-leg distances and total route distance in km, miles, and nautical miles
  • Displays the number of legs and provides a sortable leg breakdown table
  • Works entirely in the browser — no data is sent to any server

Supported code formats

Format Length Example Used by
IATA 3 letters LHR, JFK, SIN Airlines, booking platforms, baggage tags
ICAO 4 letters EGLL, KJFK, WSSS Air traffic control, flight planning, simulators

Both formats can be mixed in the same route (e.g. JFK-OMDB-SYD).

Use cases

  • Trip planning: Estimate total flying distance before booking a multi-city itinerary
  • Aviation enthusiasts: Explore and visualize long-haul routes, stopovers, and around-the-world trips
  • Frequent flyer tracking: Calculate how many kilometers a planned route covers for loyalty program estimates

Tips

  • Use hyphens between codes for readability: ATL-LHR-HND reads more clearly than ATL LHR HND
  • ICAO codes are especially useful when an airport lacks an IATA code (e.g. smaller general aviation fields)
  • The map recenters automatically on the centroid of all airports in the route