Convert coordinates from WGS 72 (EPSG:4322) to WGS 84 (EPSG:4326) — official EPSG transformation parameters, accuracy and area of use, with a free in-browser converter.
WGS 72 (EPSG:4322) is the predecessor of WGS 84, built from TRANSIT Doppler satellite observations in the early 1970s. A surprising amount of legacy data still references it: old nautical charts, satellite ephemerides, and offshore positioning records.
The WGS 72 to WGS 84 relationship is precisely defined rather than empirically fitted: a Z-axis shift of about 4.5 m, a Z-axis rotation of 0.554 arc-seconds and a scale change of 0.22 ppm. Applied correctly it is good to a couple of metres or better.
If your "WGS 72" data came through several software hops, verify which transformation was applied — some tools silently treated WGS 72 as equal to WGS 84, which leaves a systematic shift of several metres.
Try it: Greenwich Observatory, UK
Input (EPSG:4322): 0, 51.4769
The EPSG Geodetic Parameter Dataset defines 2 transformations between WGS 72 (EPSG:4322) and WGS 84 (EPSG:4326). Each applies to a specific area — pick the one whose area of use covers your data.
| Parameter | Value | Unit |
|---|---|---|
| X-axis translation(tx) | 0 | metre |
| Y-axis translation(ty) | 0 | metre |
| Z-axis translation(tz) | 4.5 | 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 |
| Parameter | Value | Unit |
|---|---|---|
| X-axis translation(tx) | 0 | metre |
| Y-axis translation(ty) | 0 | metre |
| Z-axis translation(tz) | 4.5 | 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) | 0.219 | parts per million |
The same transformation with common GIS tools and libraries:
from pyproj import Transformer
transformer = Transformer.from_crs("EPSG:4322", "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: World
+proj=longlat +ellps=WGS72 +no_defs +type=crsMore about EPSG:4322 →
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 →