The tool has gotten so much more functionality; the layout of this page doesn't really suit it anymore. Use instead the following link for the tool:
The calculations are based on GeographicLib, resulting in a very high accuracy; even on long distances.
Calculations are performed along a great circle, the shortest distance over the earth's surface. This results in curved lines on the map, which can be clearly seen on long distances.
The lines and circles can sometimes have a strange appearance; this is the case when the borders of the visible map are exceeded (the earth is a slightly flattened sphere; sometimes the shortest path runs via the poles or the "rear"). You can get a correct display of the lines and circles on a 3D projection of the earth by clicking the button "Show 3D". This option is available only if your browser and video card support WebGL.
The tool supports coordinates in several different notations.
The following calculations are available:
There is a mobile version too: