A method and apparatus for calculating the surface distance between two geographical locations are described. According to one aspect of the present invention, values are stored in a square look-up table for determining the square of a value. Also, values are stored in a linear to surface distance look-up table for determining the surface distance of a linear value. Cartesian co-ordinates of the two geographic locations and the square look-up table are then used to calculate the square of the linear distance between the two geographical locations and the linear to surface distance look-up table is used to convert the calculated square of the linear distance to a surface distance.