Tananarive (Paris) / Laborde Grid approximation to KML & KMZ

Good to know

• Datum: Treated as WGS 84, no shift (the datums agree to about a metre or better).

Convert a whole spreadsheet

1. Open the web app or the Windows app, and paste your rows from Excel or open a CSV file.
2. Under Coordinate system, search for “29702” and pick Tananarive (Paris) / Laborde Grid approximation.
3. Check one point you know on the map, then press Save KML or Save KMZ and open it in Google Earth.

Common mistakes with Tananarive (Paris) / Laborde Grid approximation

• Feet entered as metres. Tananarive (Paris) / Laborde Grid approximation is in metres. Coordinates copied from a drawing in feet must be converted first, or every point moves outwards from the grid's origin.
• Forgetting the datum. Tananarive (Paris) / Laborde Grid approximation is not on WGS 84: treated as WGS 84, no shift (the datums agree to about a metre or better). Picking a WGS 84 grid with the same projection instead leaves the points off by that amount.
• Points outside the grid's area. Tananarive (Paris) / Laborde Grid approximation is meant for Madagascar - onshore. Points well outside that area convert with growing error; the converter flags them so you can choose the right grid.
• A local site grid. If every point is off by the same distance and direction, the drawing may be on a local site grid. Calibrate on three or more known control points instead.

New to this? Read how to convert easting and northing to latitude and longitude.