How to Convert WKT to EPSG Code

Q: How do I convert WKT to EPSG code?

Paste your WKT string into epsg.io search box or use Projection Finder. The tools parse the WKT and match it against the EPSG database. Look for AUTHORITY["EPSG","4326"] in the WKT—if present, that's your EPSG code directly.

Q: Why doesn't my WKT have an EPSG code?

Older WKT formats (especially ESRI-style) often omit the AUTHORITY tag containing the EPSG code. Custom or modified projections also won't have EPSG codes. Use epsg.io or Projection Finder to match the WKT parameters against known EPSG definitions.

Q: What's the difference between OGC WKT and ESRI WKT?

OGC WKT follows ISO 19162 standard with AUTHORITY tags. ESRI WKT uses slightly different naming conventions and often omits EPSG codes. ESRI uses names like "GCS_WGS_1984" while OGC uses "WGS 84". Both represent the same CRS but with different syntax.

Published: January 2025 Read time: 5 minutes

You've got a WKT (Well-Known Text) string from a .prj file or GIS software, and you need the EPSG code. Maybe your code requires EPSG:4326 instead of a long WKT definition, or you need to look up the projection details.

This guide shows you how to convert WKT to EPSG codes quickly.

Quick Answer: How to Convert WKT to EPSG

Fastest method: Paste your WKT into epsg.io search box. It parses the string and returns matching EPSG codes. Or check if AUTHORITY["EPSG","XXXX"] already exists in your WKT—that's the EPSG code.

What Is WKT?

WKT (Well-Known Text) is a text format for representing coordinate reference systems. It defines the projection, datum, units, and parameters in a structured, readable format.

Example WKT (WGS84)

GEOGCS["WGS 84",
    DATUM["WGS_1984",
        SPHEROID["WGS 84",6378137,298.257223563,
            AUTHORITY["EPSG","7030"]],
        AUTHORITY["EPSG","6326"]],
    PRIMEM["Greenwich",0,
        AUTHORITY["EPSG","8901"]],
    UNIT["degree",0.0174532925199433,
        AUTHORITY["EPSG","9122"]],
    AUTHORITY["EPSG","4326"]]

The AUTHORITY["EPSG","4326"] at the end tells you this is EPSG:4326 (WGS84).

Method 1: Check for AUTHORITY Tag

Many WKT strings already contain the EPSG code. Search for:

AUTHORITY["EPSG","XXXX"]

The number after "EPSG" is your code. In the example above, it's 4326.

Where to Find It

Geographic CRS: Look at the end of GEOGCS[...]
Projected CRS: Look at the end of PROJCS[...]
May appear multiple times: Datum, spheroid, and CRS each can have AUTHORITY tags

Method 2: Use epsg.io

Go to epsg.io
Paste your entire WKT string into the search box
The site parses the WKT and shows matching EPSG codes

This works even if your WKT doesn't have an AUTHORITY tag—epsg.io matches the projection parameters.

Method 3: Use Projection Finder

If you have a file (Shapefile with .prj, GeoTIFF, etc.):

Upload to projectionfinder.com
The tool extracts the CRS and shows the EPSG code
Verify visually on the map preview

Got a File Instead of WKT?

Drop your Shapefile or GeoTIFF and get the EPSG code automatically.

Open Projection Finder

OGC WKT vs ESRI WKT

There are two main WKT flavors, which can cause confusion:

Feature	OGC WKT	ESRI WKT
Standard	ISO 19162	ESRI proprietary
AUTHORITY tag	Usually present	Often missing
WGS84 name	`"WGS 84"`	`"GCS_WGS_1984"`
Common source	GDAL, PostGIS, QGIS	ArcGIS, .prj files

ESRI WKT Example (No AUTHORITY)

GEOGCS["GCS_WGS_1984",
    DATUM["D_WGS_1984",
        SPHEROID["WGS_1984",6378137,298.257223563]],
    PRIMEM["Greenwich",0],
    UNIT["Degree",0.017453292519943295]]

This is WGS84 (EPSG:4326) but has no AUTHORITY tag. Use epsg.io to match it.

Method 4: Python with pyproj

from pyproj import CRS

wkt = '''GEOGCS["WGS 84",DATUM["WGS_1984",
    SPHEROID["WGS 84",6378137,298.257223563]],
    PRIMEM["Greenwich",0],
    UNIT["degree",0.0174532925199433]]'''

crs = CRS.from_wkt(wkt)
print(f"EPSG: {crs.to_epsg()}")  # Output: 4326

Method 5: GDAL/ogr2ogr

# From a .prj file
gdalsrsinfo -o epsg yourfile.prj

# From WKT string
echo 'GEOGCS["WGS 84"...]' | gdalsrsinfo -o epsg /vsistdin/

Common WKT → EPSG Mappings

WKT Name	EPSG	Description
`GCS_WGS_1984` / `WGS 84`	4326	GPS coordinates (lat/lon)
`WGS_1984_Web_Mercator`	3857	Google Maps, web tiles
`NAD_1983` / `NAD83`	4269	North American Datum
`British_National_Grid`	27700	UK Ordnance Survey
`WGS_1984_UTM_Zone_10N`	32610	UTM Zone 10 North

FAQ

How do I convert WKT to EPSG code?

Search for AUTHORITY["EPSG","XXXX"] in the WKT—that's your EPSG code. If not present, paste the WKT into epsg.io or use pyproj to match the parameters against the EPSG database.

What is WKT (Well-Known Text)?

WKT is a text markup language for representing coordinate reference systems. It defines projection parameters, datum, and units in a human-readable format used in .prj files and GIS databases.

Why doesn't my WKT have an EPSG code?

ESRI-style WKT often omits AUTHORITY tags. Custom or modified projections also won't have EPSG codes. Use epsg.io to match the WKT parameters against known EPSG definitions.

What's the difference between OGC WKT and ESRI WKT?

OGC WKT follows ISO 19162 and includes AUTHORITY tags with EPSG codes. ESRI WKT uses different naming (like "GCS_WGS_1984" vs "WGS 84") and often lacks EPSG codes. Both represent the same projections.

How do I read the EPSG code from a .prj file?

Open the .prj file in a text editor—it contains WKT. Search for AUTHORITY["EPSG", followed by a number. If not present, paste the WKT into epsg.io or upload the shapefile to Projection Finder.

Summary

Check for AUTHORITY tag — The EPSG code may already be in the WKT
Use epsg.io — Paste WKT to find matching EPSG codes
Use Projection Finder — Upload files to extract CRS automatically
Know OGC vs ESRI — ESRI WKT often lacks EPSG codes but epsg.io can match it