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Coordinates & boundariesBasic2 min readIncludes code

VN-2000 and WGS84: converting coordinates for map applications

Coordinates in land records and design drawings are usually VN-2000, while web maps use WGS84. This guide sums up the points that most often cause conversion errors.

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How VN-2000 differs from WGS84

WGS84 is the global system used by GPS, web maps and GeoJSON (degrees of latitude and longitude). VN-2000 is Vietnam’s national reference and coordinate system under Decision 83/2000/QĐ-TTg; projected VN-2000 coordinates are in metres.

Choose the right zone

Provincial cadastral maps use a TM-3 projection (3° zones) with each province’s own central meridian. With the wrong meridian, the same point lands far away.

Province or cityCentral meridianAPI key
Hanoi105°00′vn2000-tm3-482 (EPSG:5897)
Ho Chi Minh City105°45′vn2000-tm3-10545 (EPSG:9210)
Da Nang107°45′vn2000-tm3-10745 (EPSG:5899)

After the merger, a new province can include areas that used a different central meridian. For records prepared before 1 July 2025, use the former province’s zone (the projection lookup API supports era=old).

X, Y or x, y?

Vietnamese cadastral records usually write X as Northing and Y as Easting. Many GIS tools and the GMap API use x for Easting and y for Northing. A quick check: in Vietnam, Northing is about 1–2.6 million metres and Easting about 200–800 thousand metres.

Convert with the API

VN-2000 (Da Nang, 107°45′) → WGS84
curl --get 'https://cloud.gmap.vn/api/idunn/v1/transform' \
  --header 'x-api-key: public-gmap-cloud-x-api-key-demo' \
  --data 'from_crs=vn2000-tm3-10745' --data 'to_crs=wgs84' \
  --data 'x=548184.734' --data 'y=1775651.905'

# → { "lat": 16.054407, "lon": 108.202167, … }
  • from_crs, to_crs: wgs84, vn2000, vn2000-utm48n/49n or a provincial TM-3 zone.
  • WGS84 input uses lat, lon; projected VN-2000 input uses x (Easting), y (Northing).
  • Results serve applications and analytics; surveying needs professional procedures.