Convert Chatham Islands 1979 to WGS 84

Convert coordinates from Chatham Islands 1979 (EPSG:4673) 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-4673-to-epsg-4326

Official EPSG transformation from Chatham Islands 1979 to WGS 84

The EPSG Geodetic Parameter Dataset defines 1 transformation between Chatham Islands 1979 (EPSG:4673) and WGS 84 (EPSG:4326). Its parameters, accuracy and area of use are listed below.

CI1979 to WGS 84 (1)

EPSG:1081±2 m

Method:: Coordinate Frame rotation (geog2D domain)
Area of use:: New Zealand - Chatham Islands group
Scope:: Transformation of coordinates at 2m level of accuracy.

Parameter	Value	Unit
X-axis translation(tx)	174.05	metre
Y-axis translation(ty)	-25.49	metre
Z-axis translation(tz)	112.57	metre
X-axis rotation(rx)	0	arc-second
Y-axis rotation(ry)	0	arc-second
Z-axis rotation(rz)	-0.554	arc-second
Scale difference(ds)	0.2263	parts per million

Derived at 4 stations using concatenation through WGS72. Parameter vales are also used to transform CI1979 to NZGD2000 - see tfm code 1082.

Convert EPSG:4673 to EPSG:4326 in code

The same transformation with common GIS tools and libraries:

from pyproj import Transformer

transformer = Transformer.from_crs("EPSG:4673", "EPSG:4326", always_xy=True)
x, y = transformer.transform(-73.9857, 40.7484)
print(x, y)

Source: EPSG:4673 — Chatham Islands 1979

geographic system using latitude and longitude on an ellipsoid · Area of use: New Zealand - Chatham Islands group

+proj=longlat +ellps=intl +towgs84=174.05,-25.49,112.57,0,0,0.554,0.2263 +no_defs +type=crs

More about EPSG:4673 →

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 Chatham Islands 1979 to WGS 84?: The most accurate official EPSG transformation between these systems is accurate to about ±2 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:4673 →