I have a geoJSON file from Alameda County, California, that says it is based on "crs": { "type": "name", "properties": { "name": "urn:ogc:def:crs:OGC:1.3:CRS84" }}. For a given parcel, I am getting "CENTROID_X": 6049318.7740417197, "CENTROID_Y": 2116583.343045 which I am guessing is in feet but I would like to be able to convert to lat/long to be able to plot markers in Google Maps.

  • What software are you using?
    – Pointdump
    May 9 at 7:39
  • 1
    It looks like you have a coordinate system problem, see if any of the suggestions at ihatecoordinatesystems.com help.
    – Ian Turton
    May 9 at 7:51
  • 1
    What ever CRS it is, it is definitely not CRS84 (which is just lon/lat).
    – Ian Turton
    May 9 at 7:52
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    The CRS is possibly State Plane California zone 3 (III) - EPSG:2227. i.stack.imgur.com/CTkya.png If you tell us what software you are using, we could help further.
    – user2856
    May 9 at 10:54
  • Thanks everyone. Edited the question to include the file type (geoJSON) and the Open Geospatial Consortium reference. May 9 at 16:17

2 Answers 2


Credit to user2856 as well (for suggesting State Plane California zone 3):

Using node for conversion:

const proj4 = require('proj4')

const statePlaneCaliforniaZone3 = '+proj=lcc +lat_1=38.43333333333333 +lat_2=37.06666666666667 +lat_0=36.5 +lon_0=-120.5 +x_0=2000000.0001016 +y_0=500000.0001016001 +datum=NAD83 +units=us-ft +no_defs'

console.log(proj4(statePlaneCaliforniaZone3).inverse([6067236.27979723, 2123145.85667419]))

Credit to user2856

State Plane California zone 3

Confirmed in FME Desktop (Form) and reprojected to Latitude/Longitude.

enter image description here

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