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Convert ATS77 to WGS 84

Convert coordinates from ATS77 (EPSG:4122) to WGS 84 (EPSG:4326) — official EPSG transformation parameters, accuracy and area of use, with a free in-browser converter.

Direct link to this transformation: epsgtransform.com/transform/epsg-4122-to-epsg-4326

Official EPSG transformations from ATS77 to WGS 84

The EPSG Geodetic Parameter Dataset defines 3 transformations between ATS77 (EPSG:4122) and WGS 84 (EPSG:4326). Each applies to a specific area — pick the one whose area of use covers your data.

ATS77 to WGS 84 (1)

EPSG:1688±1.5 mBest accuracy
Method:
NTv2
Area of use:
Canada - New Brunswick
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.

Grid file: NB7783v2.gsb

Parameter file is from ATS77 to NAD83(CSRS)v2 (1) (code 9237) assuming that NAD83(CSRS)v2 is equivalent to WGS 84 within the accuracy of the transformation.

ATS77 to WGS 84 (2)

EPSG:1689±1.5 m
Method:
NTv2
Area of use:
Canada - Prince Edward Island
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.

Grid file: PE7783V2.gsb

Parameter file is from ATS77 to NAD83(CSRS)v2 (2) (code 9236) assuming that NAD83(CSRS)v2 is equivalent to WGS 84 within the accuracy of the transformation.

ATS77 to WGS 84 (3)

EPSG:1851±1.5 m
Method:
NTv2
Area of use:
Canada - Nova Scotia
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.

Grid file: NS778301.gsb

Parameter file is from ATS77 to NAD83(CSRS)v3 (3) (code 9235) assuming that NAD83(CSRS)v3 is equivalent to WGS 84 within the accuracy of the transformation.

Convert EPSG:4122 to EPSG:4326 in code

The same transformation with common GIS tools and libraries:

from pyproj import Transformer

transformer = Transformer.from_crs("EPSG:4122", "EPSG:4326", always_xy=True)
x, y = transformer.transform(-73.9857, 40.7484)
print(x, y)

Source: EPSG:4122 — ATS77

geographic system using latitude and longitude on an ellipsoid · Area of use: Canada - Maritime Provinces

+proj=longlat +a=6378135 +rf=298.257 +no_defs +type=crs
More about EPSG:4122 →

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 ATS77 to WGS 84?
The most accurate official EPSG transformation between these systems is accurate to about ±1.5 m within its stated area of use. Browser-based converters approximate datum shifts with Helmert parameters; for surveying-grade work apply the official transformation (including the grid-shift files listed below) 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:4122 →