Convert Datum 73 to WGS 84

Convert coordinates from Datum 73 (EPSG:4274) to WGS 84 (EPSG:4326) — official EPSG transformation parameters, accuracy and area of use, with a free in-browser converter.

From

Input (lon, lat (decimal degrees))

Output (lon, lat (decimal degrees))

Direct link to this transformation: epsgtransform.com/transform/epsg-4274-to-epsg-4326

Official EPSG transformations from Datum 73 to WGS 84

The EPSG Geodetic Parameter Dataset defines 3 transformations between Datum 73 (EPSG:4274) and WGS 84 (EPSG:4326). Each applies to a specific area — pick the one whose area of use covers your data.

Datum 73 to WGS 84 (4)

EPSG:1987±1 mBest accuracy

Method:: Coordinate Frame rotation (geog2D domain)
Area of use:: Portugal - mainland - onshore
Scope:: Medium accuracy applications.

Parameter	Value	Unit
X-axis translation(tx)	-239.749	metre
Y-axis translation(ty)	88.181	metre
Z-axis translation(tz)	30.488	metre
X-axis rotation(rx)	-0.263	arc-second
Y-axis rotation(ry)	-0.082	arc-second
Z-axis rotation(rz)	-1.211	arc-second
Scale difference(ds)	2.229	parts per million

Datum 73 to WGS 84 (1)

EPSG:1658±2 m

Method:: Position Vector transformation (geog2D domain)
Area of use:: Portugal - mainland - onshore
Scope:: (null/copy) Approximation for medium and low accuracy applications assuming equality between plate-fixed static and earth-fixed dynamic CRSs, ignoring static/dynamic CRS differences.

Parameter	Value	Unit
X-axis translation(tx)	-238.2	metre
Y-axis translation(ty)	85.2	metre
Z-axis translation(tz)	29.9	metre
X-axis rotation(rx)	0.166	arc-second
Y-axis rotation(ry)	0.046	arc-second
Z-axis rotation(rz)	1.248	arc-second
Scale difference(ds)	2.03	parts per million

Parameter values from Datum 73 to ETRS89 (1) (code 1657). Assumes ETRS89 and WGS 84 can be considered the same to within the accuracy of the transformation. Replaced by Datum 73 to WGS 84 (4) (tfm code 1987).

Datum 73 to WGS 84 (3)

EPSG:1983±5 m

Method:: Geocentric translations (geog2D domain)
Area of use:: Portugal - mainland - onshore
Scope:: Low accuracy applications.

Parameter	Value	Unit
X-axis translation(tx)	-223.237	metre
Y-axis translation(ty)	110.193	metre
Z-axis translation(tz)	36.649	metre

Convert EPSG:4274 to EPSG:4326 in code

The same transformation with common GIS tools and libraries:

from pyproj import Transformer

transformer = Transformer.from_crs("EPSG:4274", "EPSG:4326", always_xy=True)
x, y = transformer.transform(-73.9857, 40.7484)
print(x, y)

Source: EPSG:4274 — Datum 73

geographic system using latitude and longitude on an ellipsoid · Area of use: Portugal - mainland - onshore

+proj=longlat +ellps=intl +no_defs +type=crs

More about EPSG:4274 →

Target: EPSG:4326 — WGS 84

geographic system using latitude and longitude on an ellipsoid · Area of use: World (by country)

+proj=longlat +datum=WGS84 +no_defs +type=crs

More about EPSG:4326 →

Frequently asked questions

How accurate is converting Datum 73 to WGS 84?: The most accurate official EPSG transformation between these systems is accurate to about ±1 m within its stated area of use. Browser-based converters approximate datum shifts with Helmert parameters; for surveying-grade work apply the official transformation in a desktop GIS.
Does my data leave the browser when I use this converter?: No. All coordinate transformations are computed locally in your browser using proj4js. The coordinates you enter are never transmitted to any server.

Need the reverse? Convert EPSG:4326 to EPSG:4274 →