Cities Distance Calculator
Calculate the straight-line (great-circle) distance between any two cities in the world.
About great-circle distances
What is a great-circle distance?
A great-circle distance — also called the as-the-crow-flies distance — is the shortest path between two points on the surface of a sphere. The great circle through two points is the circle whose plane passes through the centre of the Earth. This is the path an aircraft would follow at constant altitude if it never deviated from the straight course.
The Haversine formula
This tool uses the Haversine formula to compute the central angle between two points given their latitudes and longitudes, then multiplies by the Earth's mean radius (6 371 km):
a = sin²(Δlat/2) + cos(lat₁)·cos(lat₂)·sin²(Δlon/2)
d = 2R · arcsin(√a)
Great-circle vs road distance
Great-circle distance is always shorter than road distance because roads follow terrain, borders, and urban layouts. For a Paris–Tokyo flight (~9 700 km great-circle), the actual flight path is longer because aircraft avoid certain airspaces. The difference between great-circle and road distance is typically 20–50% for medium distances.
Related tool
If you want to understand the mathematics behind spherical distances, see our Distance on a Sphere calculator, which lets you enter any two coordinates directly and walks you through the geometry step by step.