Donaldson R F Distance Between Cities
Find the straight-line (great-circle) distance between two cities.
This is the straight-line ("great-circle") distance "as the crow flies" — not driving or flight route distance, which is typically longer. City lookup uses OpenStreetMap's free geocoding service; coordinate mode works out the distance directly from latitude/longitude, with no lookup. Also shown: the geographic midpoint (the point halfway along the great-circle path between A and B) and each point's antipode (the point on the exact opposite side of the Earth).
Related tools: Coordinates Converter, Bearing & Azimuth Converter, Land Area from Coordinates.
Source / Last verified: standard great-circle (haversine) distance formula for a spherical Earth, mean radius 6,371.0088 km (International Union of Geodesy and Geophysics, IUGG, mean radius R₁) — read/checked 1 October 2026. This is a spherical approximation (ignores the Earth's slight equatorial bulge), accurate to within about 0.5% for most city-pair distances, which is standard for this kind of straight-line calculator.