Portugal Coordinate Converter Military & Geographic Coordinates to GPS
ENPT

How to convert military coordinates to GPS

A step-by-step guide, from the numbers on the map to a pin in Google Maps.

In short: enter X (M) and Y (P), choose “Portuguese Military Grid (EPSG:20790)” (or the system named on your document), press Convert Coordinates, then copy the latitude and longitude or open the point in Google Maps.

  1. Find the two values. Locate the X (M, easting) and Y (P, northing) values in metres. On military maps M comes first and P second.
  2. Identify the coordinate system. Read the map legend or document. Military maps of mainland Portugal normally use Datum Lisboa / Hayford-Gauss Militar (EPSG:20790). Modern documents use PT-TM06 (EPSG:3763).
  3. Enter the values. Type X and Y into the converter. A dot or a comma as the decimal separator both work; do not use thousands separators.
  4. Select the system and method. Choose the coordinate system. For historical datums keep the recommended DGT NTv2 grid method.
  5. Convert and verify. Press Convert Coordinates. Check that the point appears where you expect on the map; read any warnings.
  6. Use the GPS coordinates. Copy latitude and longitude, copy the DMS values, or open the point directly in Google Maps.

Common mistakes

  • Swapping X and Y. X (M) is the east–west value and comes first. If the result is far from Portugal, the converter checks whether swapping the values would fit and tells you.
  • Choosing the wrong system. PT-TM06, Datum 73 and Datum Lisboa grids give results only a few metres apart, so a wrong choice is not always obvious. Confirm the system from the source.
  • Thousands separators. “186.878,12” is rejected on purpose: the site never guesses whether a dot or comma groups thousands. Type 186878.12, 186878,12 or 186 878,12.
  • Kilometres instead of metres. Some documents write coordinates in km (e.g. 186.878). Convert them to metres first.

Opening the result in Google Maps

The “Open in Google Maps” button uses the official URL format https://www.google.com/maps/search/?api=1&query=LAT%2CLON with WGS84 decimal degrees, so the pin lands exactly on the converted point.

Going the other way

To obtain military or PT-TM06 coordinates from a GPS position, use the “GPS to Military Coordinates” tab: enter latitude and longitude (decimal or degrees, minutes and seconds) and the site returns X/Y in every Portuguese system.

Open the converter →

Convert Coordinates →