Great Circle Distance Calculator
Why Flight Paths Curve on a Flat Map
A straight line drawn on a flat map projection is almost never the shortest actual path between two points on a sphere — that's why long-haul flight tracker apps show curved routes arcing up toward the poles instead of a straight line across the map. That curve is the great circle route: the true shortest path along Earth's surface. This calculator computes its length directly from two coordinate pairs.
The Formula
c = 2·atan2(√a, √(1−a))
d = R × c, R = 6371 km (mean Earth radius)
This is the haversine formula — the same underlying spherical-trigonometry method used across navigation, aviation, and mapping software wherever a great-circle distance is needed.
Worked Example
Los Angeles International Airport (33.9425° N, 118.4081° W) to John F. Kennedy International Airport (40.6413° N, 73.7781° W):
| Unit | Distance |
|---|---|
| Kilometers | 3,974.26 km |
| Miles | 2,469.49 mi |
| Nautical miles | 2,145.93 nmi |
Where This Calculation Matters
- Flight planning — airlines and pilots use great-circle distance in nautical miles as the baseline for fuel planning, before adjusting for wind, air traffic routing, and airspace restrictions.
- Maritime navigation — ocean voyages follow great-circle routes for the same reason: the shortest possible track across open water.
- Satellite and telecommunications planning — ground station coverage and link budgets factor in great-circle distances to orbiting or relay points.
How to Use This Calculator
- Enter the origin latitude and longitude in decimal degrees.
- Enter the destination latitude and longitude in decimal degrees.
- Select Calculate to get the great circle distance in kilometers, miles, and nautical miles.
Related Calculations
Need the initial heading to fly or sail along that route? See the Compass Bearing Calculator. For a general point-to-point distance without nautical units, use the Distance Between Coordinates Calculator.