Land records · Parcel maps · October 7, 2026
What Is WGS84? GPS Coordinates and Datums
What is WGS84? The global datum behind GPS and web maps. How WGS84 relates to NAD83, why coordinates can shift, and what it means for parcel maps.
What is WGS84? WGS84, the World Geodetic System 1984, is a global reference system that defines the shape of the earth and a coordinate framework for locating points. It is the datum used by GPS, so latitude and longitude from phones and GPS devices are usually in WGS84. Web maps and online mapping services also rely on WGS84-based coordinates. In North America, WGS84 and NAD83 were nearly identical when created but now differ by about a meter or two because of plate movement and refinements. This page is general land-records background, not legal advice.
What a datum does
A datum defines a model of the earth’s shape and an origin for coordinates. Different datums give slightly different coordinates for the same point. See what NAD27 and NAD83 mean on a plat.
WGS84 vs NAD83
| Datum | Main use | Difference |
|---|---|---|
| WGS84 | GPS, global mapping | Global, tied to earth’s center |
| NAD83 | U.S. surveying and GIS | Tied to the North American plate |
The difference of about 1 to 2 meters matters for precise surveying but not for general mapping.
Coordinate codes
GIS software uses codes to identify systems. EPSG:4326 refers to WGS84 latitude and longitude. Web maps often use EPSG:3857, a Web Mercator projection based on WGS84.
WGS84 with UTM and state plane
WGS84 coordinates can be projected into UTM zones. County data often uses state plane coordinates on NAD83.
Why parcel lines may not line up
When parcel data in NAD83 state plane is overlaid on WGS84 imagery without proper transformation, lines can appear shifted. Parcel maps are also not survey-accurate. See how to use a county GIS viewer.
Updates
WGS84 has been updated several times to improve accuracy. New U.S. datums are planned to replace NAD83, which will also change coordinates slightly.
Example
A homeowner records GPS coordinates of a property corner pin with a phone, giving WGS84 latitude and longitude. Comparing with a county GIS layer in NAD83 shows a small offset, along with phone accuracy limits of several meters. For precise work, a surveyor uses survey-grade equipment and NAD83.
Practical tips
When sharing coordinates, state the datum. When importing GPS points into GIS, set the correct coordinate system.
Phone GPS accuracy
Phone GPS is typically accurate to several meters in open sky, less near trees or buildings, so it should not be used to set property lines.
Datum shifts in older records
Older plats and county maps may use NAD27, which can differ from WGS84 and NAD83 by tens of meters in some places. When comparing old records to GPS data, a datum mismatch can explain large offsets. GIS tools can transform between datums if the source datum is known.
Bottom line
WGS84 is the global datum behind GPS and web maps. It differs slightly from NAD83, used for U.S. surveying and county GIS. Always note the datum when using coordinates, and rely on surveyors for boundary precision. Explore parcel maps via the Platbookmapper map.
What is wgs84 FAQ
What is WGS84?
The global datum used by GPS.
Is WGS84 the same as NAD83?
Very close, but they differ by about 1 to 2 meters.
What is EPSG 4326?
The code for WGS84 latitude and longitude.
Why do parcel lines shift on maps?
Datum and projection differences, plus data accuracy.
Can I use phone GPS to find property lines?
Not precisely; use a surveyor.