I was given an unprojected coordinate in the form of lat, lon and I am using pyproj to convert to projected coordinate as such:

from pyproj import Proj

# New Jersey
lat = 40.704895
lon = -74.094994

wgs84 = Proj(proj='utm', zone=18, ellps='clrk66')
x, y = wgs84(sample_data['lon'], sample_data['lat'])

# x = 576453.375, y = 4506180.871
# 576453 meters east and 4508180 meters north of the zone's origin

I'd like to know the origin (0, 0) of the UTM zone 18N. I tried using inverse conversion with

wgs84(0, 0, inverse=True)

I got (-79.48869479772156, 0.0) which means it's 79 meters south and right at the Prime Meridian which seems wrong.

  • It means it is 79 degrees West of the Prime Meridian and starts at the equator, as you would expect if you looked at the map of UTM zones. Feb 2, 2016 at 7:32

3 Answers 3


Many projected coordinate systems use a false Easting and/or a false Northing to avoid negative coordinates and/or to reduce potential ambiguities with other CRS of the same region.

In the case of UTM 18N, the origin of the projection, in lat long, is (0°, -75°), but the false easting is 500 000 m meaning that the XY coordinate system has been shifted.

Note that when you invert the projection the result is back in Lat/long. So your result mean that you are on the equator with a longitude of -79.5, which comes from -75°(central meridian) - 500/111 (false easting approximately converted in degrees)

Projection: Transverse_Mercator (in your case on the NAD1927 ellipsoid)

False_Easting: 500000,0

False_Northing: 0,0

Central_Meridian: -75,0

Scale_Factor: 0,9996

Latitude_Of_Origin: 0,0

Linear Unit: Meter (1,0)


The units of WGS84 are degrees, so your result says 79 degrees west of the Greenwich prime meridian.

Generally, UTM coordinates have a false easting of 500km, so the origin is really 500km west of the UTM 18N meridian at 75° West cutting the equator.


Zone 1 covers longitude 180° to 174° W, hence it's origin is (177° W,0° N). similarly moving eastward Zone 2 covers longitude 174° to 168° W, with origin (171° W,0° N). so Zone 18 is 78° W to 72° W, with origin (75°W, 0°N)

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