Convert KKJ to ETRS89

Convert coordinates from KKJ (EPSG:4123) to ETRS89 (EPSG:4258) — 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-4123-to-epsg-4258

Official EPSG transformation from KKJ to ETRS89

The EPSG Geodetic Parameter Dataset defines 1 transformation between KKJ (EPSG:4123) and ETRS89 (EPSG:4258). Its parameters, accuracy and area of use are listed below.

KKJ to ETRS89 (1)

EPSG:1638±1.5 m

Method:: Position Vector transformation (geog2D domain)
Area of use:: Finland - onshore
Scope:: Transformation of coordinates at 1m to 2m level of accuracy.

Parameter	Value	Unit
X-axis translation(tx)	-90.7	metre
Y-axis translation(ty)	-106.1	metre
Z-axis translation(tz)	-119.2	metre
X-axis rotation(rx)	4.09	arc-second
Y-axis rotation(ry)	0.218	arc-second
Z-axis rotation(rz)	-1.05	arc-second
Scale difference(ds)	1.37	parts per million

Parameter values derived from ETRF89 (EUREF-89) coordinates based on the Finnish GPS campaign in 1992 (“GPS-Suomi”). May be taken as approximate transformation KKJ to WGS 84 - see code 1639. Replaced by KKJ to EUREF-FIN (2) (code 10098).

Convert EPSG:4123 to EPSG:4258 in code

The same transformation with common GIS tools and libraries:

from pyproj import Transformer

transformer = Transformer.from_crs("EPSG:4123", "EPSG:4258", always_xy=True)
x, y = transformer.transform(-73.9857, 40.7484)
print(x, y)

Source: EPSG:4123 — KKJ

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

+proj=longlat +ellps=intl +towgs84=-96.062,-82.428,-121.753,4.801,0.345,-1.376,1.496 +no_defs +type=crs

More about EPSG:4123 →

Target: EPSG:4258 — ETRS89

geographic system using latitude and longitude on an ellipsoid · Area of use: Europe - ETRF by country

+proj=longlat +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +no_defs +type=crs

More about EPSG:4258 →

Frequently asked questions

How accurate is converting KKJ to ETRS89?: 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 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:4258 to EPSG:4123 →