I have a detailed topo map for an irregular shaped property. It has boundary lines expressed like this, for example; S76˚45'08"W and S59˚38'24"W. The map also notes how long each boundary line is. I need a beginning reference point in GPS coordinates to mark a physical point on the property (using my cell phone's compass feature), and then need to use the info on the map to stake out the property border.

How do I calculate the GPS coordinates from where these two lines intersect?

  • If this is a surveyors map, there should be some reference to a trigonomical point nearby. You might have to ask the surveyor about it.
    – AndreJ
    Jul 2, 2017 at 5:30
  • Are you trying to stake property or locate the existing monuments. Your phone may be helpful in locating the monuments but should not be used to stake property boundaries. Jul 2, 2017 at 16:06

1 Answer 1


What you have there are Bearings of the Boundary Line. There are four bearing quadrants in a circle. To relate the bearings to a north based azimuth

0-90 degree azimuth = the North East Quadrant. N DD-MM-SS E
The bearing would be the same as the azimuth.

90.0001-180.0000 degree azimuth = the South East Quadrant S DD-MM-SS E To convert a Southeast bearing to an azimuth you subtract the bearing from 180 degrees.

180.0001-270.0000 degree azimuth = the South West Quadrant S DD-MM-SS W To convert a Southwest bearing to an azimuth, you would add the bearing to 180 degrees. The azimuths of the two bearings you have listed would be 256-45-08 and 239-38-24 respectively.

270.0001-360.0000 degree azimuth = North West Quadrant N DD-MM-SS W To convert a Northwest bearing to an azimuth, you subtract the bearing from 360 degrees.

Using the bearings, and associated distances you can navigate the property lines for the fun of it, but I would not trust the accuracy of the position provided by your phone, or the directional accuracy of the compass in your phone to lay out a property line.

That job is best left for a Land Surveyor to do unless the corners, or angle points of the boundary are well marked, and intervisible.

If you are in the United States, it is illegal in most states for someone to determine a property boundary unless they are a Registered Land Surveyor in that state.

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