Distance Between Coordinates (Haversine)
Enter two sets of latitude and longitude and get the great-circle distance between them — the shortest path over the surface of the Earth — in kilometres, miles, and nautical miles.
Great-circle distance
Straight-line, not road distance
Great-circle distance is the length of the shortest arc between two points on a sphere. It is the number pilots and mariners plan around, and the baseline every routing engine starts from before it adds the twists of real roads. Because it ignores terrain, one-way systems, and detours, it is always a lower bound: the actual route distance can only be equal to or longer than the figure here.
The calculation uses the Haversine formula with a mean Earth radius of 6,371 km. That spherical assumption keeps things simple and is accurate to a fraction of a percent — plenty for comparing routes, sizing a journey, or checking how far apart two waypoints really are.
Frequently Asked Questions
What is the Haversine formula?
The Haversine formula computes the great-circle distance between two points on a sphere from their latitudes and longitudes. It uses the haversine of the differences in latitude and longitude to stay numerically stable even for points that are very close together, then multiplies the resulting central angle by the Earth's radius.
Is this the driving distance?
No. This is the great-circle or "as the crow flies" distance — the shortest path over the surface of the Earth. A real road, rail, or trail route follows terrain and infrastructure and is always longer; for driving distance you need a routing engine that knows the road network.
What format should the coordinates be in?
Enter decimal degrees, for example 51.5074 and -0.1278. Latitudes run from -90 (south) to 90 (north) and longitudes from -180 (west) to 180 (east). If you have degrees-minutes-seconds, convert them first with the coordinate converter.
Why offer nautical miles?
One nautical mile was originally defined as one minute of latitude along a meridian, which makes it the natural unit for marine and air navigation. The tool reports kilometres, statute miles, and nautical miles so the same fix works on a chart, a road map, or a plotter.
How accurate is it?
The Haversine formula treats the Earth as a perfect sphere, so it is typically within about 0.3% of the true distance. For most navigation and planning that is more than close enough; geodesists who need millimetre accuracy over long baselines use ellipsoidal methods such as Vincenty's formulae instead.
Educational reference only. Great-circle distance assumes a spherical Earth and is not the distance of any real road, rail, or air route.