Javascript geodetic azimuth and distance calculator
This calculator is based on "Vincenty's Formula" for elliptical Earth. It is not based on the "Great circle formula" which is innacurate and assumes a "round" Earth.

Comprises two programs essentially the same as INVERSE & FORWARD available at National Geodetic Survey.
INVERSE - computes the geodetic azimuth (bearing) and distance between two points, given their geographic positions. FORWARD - computes the geographic position of a point, given the geodetic azimuth (bearing) and distance from a point with known geographic position.

Enter lat/long. of two points, select distance units and Earth model and click "compute". Lat/long.'s may be entered as:
DD.DD or DD:MM.MM  or DD:MM:SS.SS formats.

Note that if either point is very close to a pole, the course may be inaccurate, because of its extreme sensitivity to position and inevitable rounding error.

Input Data

Lat. A

Long. A
       

Lat. B

Long. B
Output

Azim. A to B

Azim. B to A

Distance

Distance Units: Earth model:

Enter lat/long. of initial point, true course and distance. Select distance units and Earth model and click "compute". Note that the starting point cannot be a pole.

Input data

Lat. A

Long. A
     

Azim. A to B

  

Distance
 
Output

Lat. B

Long. B

Distance Units: Earth model:

User Defined

If "user defined" is the selected Earth model above, enter the spheroid parameters here:

Major radius i.e. equatorial Earth radius (a) in km: Inverse flattening 1/f:

Note that if either point is very close to a pole, the course may be inaccurate, because of its extreme sensitivity to position and inevitable rounding error.

Geodetic azimuth and distance calculator © 2003