Skip to main content
Technical

WGS84 (World Geodetic System 1984)

The global reference ellipsoid used by GPS. Lat-lon values are WGS84-based; systems like Google Maps and TKGM Parcel Query use this datum.

WGS84 (World Geodetic System 1984) is the worldwide standard geodetic system and reference ellipsoid developed by the US Department of Defense and used as the official reference system for GPS. It mathematically defines the Earth's shape and size: semi-major axis 6,378,137 m (equatorial radius), semi-minor axis 6,356,752.314 m (polar radius), flattening 1/298.257223563.

Every GPS receiver delivers coordinates in WGS84 by default. Google Maps, Apple Maps, OpenStreetMap and nearly all web maps use WGS84 geographic coordinates (EPSG:4326). Lat-lon data from mobile apps is typically in WGS84.

Differences between WGS84 and Türkiye's cadastral system (ITRF96) are extremely small (centimetre scale); for most applications they can be considered equivalent. However, for high-precision engineering measurements, TUSAGA-Aktif (Turkey's National Fixed GNSS Stations Network) provides correction signals in ITRF96 datum.

EPSG codes: WGS84 geographic is EPSG:4326; WGS84 + Web Mercator projection is EPSG:3857; WGS84 + UTM Zone 36N is EPSG:32636. Datum must be specified by EPSG code in GIS applications.

Examples

  • 1.A tourist pastes a Google Maps link (41.0082°N, 28.9784°E) into Drozero; the system recognises it as WGS84 and finds the parcel on the map.
  • 2.Aerial measurements by drone use a WGS84-based GPS module; output ortophoto is served in both EPSG:4326 and EPSG:32636 projections.
  • 3.A surveyor using RTK correction in ITRF96 from TUSAGA-Aktif can publish WGS84 results directly without datum transformation (<10 cm difference).

Frequently Asked Questions

Is WGS84 the same as ITRF96?expand_more
In practice yes, but technically different. WGS84 is the US's global system, ITRF96 is the 1996 epoch of the international terrestrial reference frame. Türkiye's cadastre officially uses **ITRF96**; general GPS/mobile uses **WGS84**. Sub-centimetre differences are insignificant for most real estate/zoning applications.
Why can WGS84 coordinates change?expand_more
Tectonic plates move several cm annually. Each new version of WGS84 (G730, G873, G1150, G1674, G2139) introduces small corrections. The Anatolian Plate drifts ~2-3 cm/year northwest; coordinates shift ~50 cm over 20 years. High-precision engineering records an **epoch** (measurement date).
How do I convert WGS84 degrees to metres?expand_more
At the equator, 1° longitude ≈ 111 km. With increasing latitude (going north), 1° longitude decreases to **cos(latitude) × 111 km**: for İstanbul (41°) ~83 km/°. 1° latitude is always ≈ 111 km. For small distance calculations, project to UTM.
What datum are Google Maps coordinates in?expand_more
WGS84. Lat-lon displayed in Google Maps interface in decimal degrees format are WGS84 (EPSG:4326). Transfer to land registry systems for Türkiye is typically automatic; for sub-metre precision, use an ITRF96 conversion tool.

Related Terms

Coordinate SystemUTM (Universal Transverse Mercator)GIS (Geographic Information System)

Sources

  • • US DoD - World Geodetic System 1984 Technical Report (NIMA TR8350.2)
  • • TKGM TUSAGA-Aktif Network Technical Documentation
  • • International Earth Rotation and Reference Systems Service (IERS) - ITRF2020

Try the FAR/GCR calculator

Calculate total floor area, storey count and estimated unit count in seconds from parcel m² and zoning values.

Go to Calculatorarrow_forward

Last updated: 2026-04-24