GeoJSON uses the World Geodetic System 1984 (WGS 84) [WGS84] datum, with longitude and latitude units of decimal degrees.

WGS 84 is the reference system GPS uses. Its EPSG code is 4326. Coordinates in it are angles (latitude from -90 to 90, longitude from -180 to 180) written as decimal degrees: 5.324871, not 5°19'29.5".

Coordinates in any other system "must be converted" before upload (GeoJSON File Description, Introduction). See UTM to WGS 84.

Sources

Last verified against these sources on .