# Converting projected coordinates to lat/lon using Python

This site returns

``````Point:
X: -11705274.6374
Y: 4826473.6922
``````

when you search with the first key value of 000090, as an example. I assume that this is a spatial reference.

I am looking for instructions, or examples, of how to convert this to latitude and longitude using Python.

• That site returns: "Access to the application you were trying to use has been blocked in accordance with County policy. Please contact your organization's Service Desk if you believe this is in error." Jul 6 at 4:43

The simplest way to transform coordinates in Python is pyproj, i.e. the Python interface to PROJ.4 library. In fact:

``````from pyproj import Proj, transform

inProj = Proj(init='epsg:3857')
outProj = Proj(init='epsg:4326')
x1,y1 = -11705274.6374,4826473.6922
x2,y2 = transform(inProj,outProj,x1,y1)
print x2,y2
``````

returns `-105.150271116 39.7278572773`

## EDIT based on Marc's comment:

pyproj 2.4 gives a FutureWarning about deprecated `Proj` initialization with the `init=` syntax. The updated syntax is identical but without the `init=`. Like this:

``````inProj = Proj('epsg:3857')
outProj = Proj('epsg:4326')
``````
• pyproj 2.4 gives a FutureWarning about deprecated Proj() initialization with the `init=` syntax. The updated syntax is identical but without the `init=`. Like this: `inProj = Proj('epsg:3857')` and `outProj = Proj('epsg:4326')` Dec 19, 2019 at 21:35
• I removed the `'init='` based on the edit, but my output of `transform(inProj,outProj,x1,y1)` gave me `(latitude, longitude)` instead of `(longitude, latitude)`. Anybody knows why ? Feb 18, 2020 at 15:18
• Feb 22, 2020 at 17:17
• This might be helpful to reference: pyproj4.github.io/pyproj/stable/… Jan 26, 2021 at 1:20
• This will also be good to reference: pyproj4.github.io/pyproj/stable/… Jan 26, 2021 at 1:21

By default the site you linked to uses the Spatial Reference System EPSG 3857 (WGS84 Web Mercator). I found this information here.

You can either specify another Spatial Reference System by entering the desired EPSG into the form under `Spatial Reference` or you can convert the returned coordinates with Python.

For instance you can use the GDAL Python bindings to convert this point from the projected coordinate system (EPSG 3857) to a geographic coordinate system (EPSG 4326).

``````from osgeo import ogr
from osgeo import osr

pointX = -11705274.6374
pointY = 4826473.6922

# Spatial Reference System
inputEPSG = 3857
outputEPSG = 4326

# create a geometry from coordinates
point = ogr.Geometry(ogr.wkbPoint)

# create coordinate transformation
inSpatialRef = osr.SpatialReference()
inSpatialRef.ImportFromEPSG(inputEPSG)

outSpatialRef = osr.SpatialReference()
outSpatialRef.ImportFromEPSG(outputEPSG)

coordTransform = osr.CoordinateTransformation(inSpatialRef, outSpatialRef)

# transform point
point.Transform(coordTransform)

# print point in EPSG 4326
print point.GetX(), point.GetY()
``````

This returns for your point the coordinates of `-105.150271116 39.7278572773`.

• @Thomas it is returning 39.7278572773 -105.150271116, why is it flipping coordinates? Mar 27 at 10:23

When using pyproj, note the differences from various releases in how it is used to transform data. Here are a few examples using new/old capabilities based on the question:

# Using pyproj >= 2.2.0

``````import pyproj
print(pyproj.__version__)  # 2.4.1
print(pyproj.proj_version_str) # 6.2.1

proj = pyproj.Transformer.from_crs(3857, 4326, always_xy=True)

x1, y1 = (-11705274.6374, 4826473.6922)
x2, y2 = proj.transform(x1, y1)
print((x2, y2))  # (-105.15027111593008, 39.72785727727918)
``````

# Using pyproj <= 1.9.6

``````import pyproj
print(pyproj.__version__)  # 1.9.6
print(pyproj.proj_version_str) # 4.9.3

inProj = pyproj.Proj(init='epsg:3857')
outProj = pyproj.Proj(init='epsg:4326')

x1, y1 = (-11705274.6374, 4826473.6922)
x2, y2 = pyproj.transform(inProj, outProj, x1, y1)
print((x2, y2))  # (-105.15027111593008, 39.72785727727918)
``````

There are a few considerations with the different versions of PROJ/pyproj:

• `transform` for older versions always return the same axis order of "x, y" or "longitude, latitude", whereas PROJ 6+ is the order as defined by EPSG, unless an option like `always_xy=True` is specified
• `Proj` is limited to converting between geographic and projection coordinates within one datum, whereas the newer `Transformer` takes into account datum shifts, and is recommended for newer pyproj use

afalciano has the right answer but wanted to include a variant usage of pyproj.

It does require you know the proj4 string and is a tiny bit faster.

``````import pyproj
p = pyproj.Proj("+proj=merc +lon_0=0 +k=1 +x_0=0 +y_0=0 +a=6378137 +b=6378137 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs")
lon, lat = p(x, y, inverse=True)
print lat, lon
``````
• You don't need the proj4 string, substitute the second line for `p = pyproj.Proj(init='epsg:3857')` and the result is the same. Sep 15, 2016 at 0:08
• The result is the same but last I checked this was a tiny bit faster. Sep 17, 2016 at 17:03
• Even though it was not the intention of this answer, it is particularly useful when you have a totally custom projection, which is not listed in the EPSG-repository. Jan 13, 2020 at 13:51

The output is not a spatial/coordinate reference system, it's a pair of coordinates. You need to know what the spatial reference is to reproject the coordinates.

However, that's not required in this case. Just pass an appropriate output spatial reference to the service and it will return the coordinates in Lon/Lat.

Here is the page with output coordinates in Lon/Lat format using the WGS-84 geographic spatial reference system (EPSG 4326).

Tried the code suggested by Marcel Wilson and it is faster:

``````from pyproj import Proj, transform
import time
import pyproj

# Test 1 - 0.0006158 s
start=time.time()
inProj = Proj(init='epsg:3857')
outProj = Proj(init='epsg:4326')
x1,y1 = -11705274.6374,4826473.6922
x2,y2 = transform(inProj,outProj,x1,y1)
end=time.time()
print(y2,x2)
print('%.7f' % (end-start))

# Test 2 - 0.0000517 s --- factor 11,9
start=time.time()
x,y = -11705274.6374,4826473.6922
p = pyproj.Proj("+proj=merc +lon_0=0 +k=1 +x_0=0 +y_0=0 +a=6378137 +b=6378137 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs")
lon, lat = p(x, y, inverse=True)
end=time.time()
print(lat, lon)
print('%.7f' % (end-start))
-----------------

39.72785727727918 -105.15027111593008
0.0006158
39.72785727727918 -105.15027111593008
0.0000517
``````

Please note that the `transform` function of `pyproj` accepts also `arrays`, which is quite useful when it comes to dataframes

``````import pandas as pd
from pyproj import Proj, transform

df = pd.DataFrame({'x': [-11705274.6374]*100,
'y': [4826473.6922]*100})
inProj, outProj = Proj(init='epsg:3857'), Proj(init='epsg:4326')
df['x2'], df['y2'] = transform(inProj, outProj, df['x'].tolist(), df['y'].tolist())
``````

I found this post when looking for ways of doing this within QGIS. As described here, the method used looks like so:

``````def convertProjection(self,x,y,from_crs,to_crs):
crsDest = QgsCoordinateReferenceSystem(to_crs)
pt = xform.transform(QgsPoint(x,y))
return pt.x, pt.y

# Remove the "EPSG:" part
from_crs = 3857
to_crs = 4326
x = -11705274.6374
y = 4826473.6922
lon, lat = self.convertProjection(x,y,from_crs, to_crs)
``````

This is a shorter version of ustroetz's answer since the `ogr.wkbPoint` geometry is not required for a point.

``````from osgeo import osr

pointX = -11705274.6374
pointY = 4826473.6922
pointZ = 0.0

# Spatial Reference System
inputEPSG = 3857
outputEPSG = 4326

# create coordinate transformation
inSpatialRef = osr.SpatialReference()
inSpatialRef.ImportFromEPSG(inputEPSG)

outSpatialRef = osr.SpatialReference()
outSpatialRef.ImportFromEPSG(outputEPSG)

coordTransform = osr.CoordinateTransformation(inSpatialRef, outSpatialRef)

# transform point, height z is optional
x, y, z = coordTransform.TransformPoint(pointX, pointY, pointZ)

# print point in EPSG 4326
print(x, y)
``````

convert esri extent bbox to lat long

1. use esri javascipt api module ( client side projection, fast, no need ajax, no need internet, projection done in your browser, extremely fast)

first include css, js

This is my working example: 1. proj4js ( need ajax, internet to read projection string from website, due to website does not allow jsonp, not allow cors, you have to setup your own proxy to bypass CORS problem, not easy for normal user )

But if you already known from what to what, then you can just copy past projection string, no internet needed, all projectin done in your browser.

If you don't know project from what to what, projection wkid is dynamic generated in the runtime, then like I said previously, you must need ajax, need internet to read projection string from website on the fly, in the run time. It is not easy, because you have to bypass CORS problem.

Here is my working example: 1. use Arcgis.com hosted web service ( need internet, very slow, not reliable, if ESRI server is crowded, you might get it very slow. Every ajax request can only conver one pair of lat lng)  Here is how to project on website you can get xmin, ymin from here • Downvoted because the question is tagged `python` and this answer uses JavaScript exclusively. Also the screenshots... please don't do this on Stack Exchange. Jul 6 at 5:03