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Convert NAD27(CGQ77) to NAD83

Convert coordinates from NAD27(CGQ77) (EPSG:4609) to NAD83 (EPSG:4269) — official EPSG transformation parameters, accuracy and area of use, with a free in-browser converter.

Direct link to this transformation: epsgtransform.com/transform/epsg-4609-to-epsg-4269

Official EPSG transformations from NAD27(CGQ77) to NAD83

The EPSG Geodetic Parameter Dataset defines 2 transformations between NAD27(CGQ77) (EPSG:4609) and NAD83 (EPSG:4269). Each applies to a specific area — pick the one whose area of use covers your data.

NAD27(CGQ77) to NAD83 (1)

EPSG:1451±1 mBest accuracy
Method:
NTv1
Area of use:
Canada - Quebec
Scope:
Historic record only - now superseded - see remarks.

Grid file: PQV4.DAC

Replaced by NAD27(CGQ77) to NAD83 (2) (code 1575). Uses NT method which expects longitudes positive west; EPSG GeogCRSs CGQ77 (code 4609) and NAD83 (code 4269) have longitudes positive east.

NAD27(CGQ77) to NAD83 (2)

EPSG:1575±1.5 m
Method:
NTv2
Area of use:
Canada - Quebec
Scope:
Transformation of coordinates at 1m to 2m level of accuracy.

Grid file: CQ77NA83.GSB

Replaces NAD27(CGQ77) to NAD83 (1) (code 1451). Can be taken as approx transformation to WGS 84 - see code 1691.

Convert EPSG:4609 to EPSG:4269 in code

The same transformation with common GIS tools and libraries:

from pyproj import Transformer

transformer = Transformer.from_crs("EPSG:4609", "EPSG:4269", always_xy=True)
x, y = transformer.transform(-73.9857, 40.7484)
print(x, y)

Source: EPSG:4609 — NAD27(CGQ77)

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

+proj=longlat +ellps=clrk66 +no_defs +type=crs
More about EPSG:4609 →

Target: EPSG:4269 — NAD83

geographic system using latitude and longitude on an ellipsoid · Area of use: North America - NAD83

+proj=longlat +datum=NAD83 +no_defs +type=crs
More about EPSG:4269 →

Frequently asked questions

How accurate is converting NAD27(CGQ77) to NAD83?
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 (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:4269 to EPSG:4609 →