Commenting as a non-surveyor, that looks like the basic (Euclidean) distance formula that we all learned in basic algebra/geometry, I am looking for very small movements, not distances, less then a Mil (I hope), I am using this formula for Pile monitoring, Computing the differance between two Northing and Eastings, http://www.purplemath.com/modules/distform.htm. Note: If transformation settings for a drawing are not enabled, the Select Point, Local Northing, Local Easting, and Local Elevation . With this excel file you can calculate Distance and Bearing from coordinates easily, just you have to input the Easting and Northing values only.. | Large map | Coordinates to address