Convert coordinates from Indian 1960 (EPSG:4131) to WGS 84 (EPSG:4326) — official EPSG transformation parameters, accuracy and area of use, with a free in-browser converter.
Indian 1960 (EPSG:4131) is a regional adjustment of the Indian datum on the Everest 1830 ellipsoid, used in Vietnam and around Con Son island. It survives mainly in oil and gas concession data from offshore Vietnam, where blocks were originally defined in Indian 1960 coordinates.
The published EPSG transformations to WGS 84 are accurate to roughly ±25 m — typical for a datum fitted from a handful of stations in the satellite era's early days.
Vietnam's national system is now VN-2000 (EPSG:4756); treat Indian 1960 as a legacy frame to convert out of, and document the operation you used because concession boundaries are legally sensitive.
Try it: Ho Chi Minh City, Vietnam
Input (EPSG:4131): 106.6297, 10.8231
The EPSG Geodetic Parameter Dataset defines 3 transformations between Indian 1960 (EPSG:4131) and WGS 84 (EPSG:4326). Each applies to a specific area — pick the one whose area of use covers your data.
May be implemented as a single transformation using position vector 7-parameter geocentric transformation method with parameter values dX=+199m dY=+931m dZ=+318.9m rX=rY=0 sec rZ=+0.814 sec dS=-0.38 ppm.
| Parameter | Value | Unit |
|---|---|---|
| X-axis translation(tx) | 198 | metre |
| Y-axis translation(ty) | 881 | metre |
| Z-axis translation(tz) | 317 | metre |
Derived at 2 stations. Accuracy 25m in each axis.
| Parameter | Value | Unit |
|---|---|---|
| X-axis translation(tx) | 182 | metre |
| Y-axis translation(ty) | 915 | metre |
| Z-axis translation(tz) | 344 | metre |
Derived at 1 station. Accuracy 25m in each axis.
The same transformation with common GIS tools and libraries:
from pyproj import Transformer
transformer = Transformer.from_crs("EPSG:4131", "EPSG:4326", always_xy=True)
x, y = transformer.transform(-73.9857, 40.7484)
print(x, y)geographic system using latitude and longitude on an ellipsoid · Area of use: Asia - Cambodia and Vietnam - onshore & Cuu Long basin
+proj=longlat +ellps=evrst30 +no_defs +type=crsMore about EPSG:4131 →
geographic system using latitude and longitude on an ellipsoid · Area of use: World (by country)
+proj=longlat +datum=WGS84 +no_defs +type=crsMore about EPSG:4326 →