Use this cartographic calculation to convert, scale, or compare map, terrain, bearing, raster, or route quantities when the coordinate and unit conventions are explicitly known.

Latitude1Degrees (deg)

Required number input.

Longitude1Degrees (deg)

Required number input.

Latitude2Degrees (deg)

Required number input.

Longitude2Degrees (deg)

Required number input.

Earth Radius Kilometers (km)

Required number input.

Spherical great-circle distance in kilometres using a user-supplied Earth radius. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Distance Kilometers (km)

The resulting distance kilometers returned as a number.

• Map calculations depend on datum, projection, latitude, scale definition, magnetic-declination epoch, and whether distances are planar, rhumb-line, or geodesic. A compact formula cannot remove distortion or infer the missing reference system.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Confirm the map datum, projection, scale, and bearing convention before applying the result. Use geodesic or GIS software with current reference data when survey-grade or navigation-critical accuracy is required.

• Horizon Distance From Height

  Geometric horizon distance in kilometres for observer height and spherical Earth radius, without refraction.

• Great Circle Initial Bearing

  Initial spherical great-circle bearing from the first latitude/longitude to the second, normalized to [0,360).

• Latitude Degree To Km Fixed

  Approximate north-south kilometres per latitude degree on a spherical Earth.