Distance & Bearing Calculator
Enter two coordinates as lat, lon and read the great-circle distance in km, miles and nautical miles, the initial and final bearing with a compass heading, and the midpoint — live, in your browser.
Decimal degrees only. Latitude −90…90, longitude −180…180 (negative = south / west). Spaces optional.
Runs entirely in your browser. No coordinate you type is uploaded or logged — the geodesy maths uses a small committed library and works offline.
What this tool measures
Give it two points on the Earth — each as a latitude, longitude pair in decimal degrees — and it works out the great-circle distance between them: the shortest path over the curved surface of the planet, the route a bird or a long-haul aircraft would fly. It also reports the bearing (the compass direction from the first point to the second) and the midpoint, the coordinate exactly half-way along that shortest path. Everything recomputes the instant you change either point.
Haversine vs ellipsoidal (Vincenty) accuracy
There are two common ways to measure distance across the globe, and they differ because the Earth is not a perfect ball. The haversine formula treats the planet as a sphere of one mean radius (about 6,371 km). It is short, fast and never fails to converge, but because the Earth is flattened at the poles — the equatorial radius is about 21 km larger than the polar radius — haversine can be off by up to roughly 0.3%. The Vincenty inverse formula instead models the Earth as the WGS-84 ellipsoid, the same oblate reference shape your phone's GPS uses, and iterates until it agrees to about 0.5 mm. This tool shows the Vincenty result as the headline distance and the haversine value beside it so you can see the difference for yourself. (Vincenty's one weakness is near-antipodal points — places almost exactly opposite each other on the globe — where the iteration can fail to settle; in that rare case the haversine figure is the reliable one.)
Worked example: London → Paris
Take London at 51.5074, -0.1278 and Paris at 48.8566, 2.3522 (both city-centre reference points). The tool returns:
Notice the two distance methods agree to within 360 metres over 344 km — that is the ~0.1% spread you get at this latitude and range. The Eurostar rail journey between the two cities is about 492 km of track, roughly 43% further than the 344 km straight line, which is a good illustration of why great-circle distance is not travel distance.
Bearings and the compass
A bearing is a direction measured in degrees clockwise from true north: 0° is due north, 90° east, 180° south, 270° west. This tool labels each bearing with the nearest of the 16 traditional compass points (N, NNE, NE, ENE, E, …) so a numeric heading like 148° reads at a glance as SSE. Because the shortest path over a sphere is a great circle rather than a line of constant heading, the compass direction changes as you travel — so the initial bearing (the way you set off) differs from the final bearing (the way you are pointing when you arrive), except along the equator or a pure north–south meridian. Sailors and pilots following a great circle re-check their heading periodically for exactly this reason; a fixed-heading rhumb line is simpler to steer but always a little longer.
The midpoint
The midpoint shown is the half-way point along the great-circle path, not the naive average of the two latitudes and longitudes — those only coincide for points on the same meridian. For London → Paris it lands at 50.1886, 1.1466, near Abbeville in northern France, a little west of the straight line you might sketch on a flat map because the shortest curved path bows slightly toward the nearer pole.
Honest limits
New to the maths behind it? Great-Circle Distance Explained is a first-principles guide that works the haversine formula step by step, covers rhumb lines and bearings, and explains the honest spherical-vs-ellipsoid accuracy limit.
This is straight-line great-circle distance, not driving distance. It measures the shortest path over the surface of the Earth as the crow flies; it does not know about roads, railways, shipping lanes, terrain, one-way systems or borders. A real road trip is typically 20–40% longer than the great-circle figure, and far longer where water or mountains force a detour — so use this for as-the-crow-flies estimates, flight-distance sanity checks, radius questions and bearing/heading work, not for turn-by-turn route planning. It also assumes both points are at sea level: it ignores altitude, so it will not add the extra distance of climbing a mountain or the slant range to an aircraft overhead. Coordinates are in the WGS-84 datum (what GPS and web maps use); if your source uses a different local datum the result can shift by tens of metres.