Open Settings → Tools → Coordinate converter to enter a position manually. Coordinate tools do not require location permission.
Formats and reference systems
DD, DMS and DDM are different ways to write latitude and longitude. UTM and UPS are projections; MGRS expresses a position as a grid reference. Changing representation does not improve the source measurement.
GPSDeck preserves WGS84 geographic coordinates in saved records. Tools include WGS84-to-ECEF and local ENU conversion, UTM/UPS, MGRS and two-point distance and bearing. ENU needs a defined origin. A local coordinate without an origin is not a global position.
Heights
System altitude approximates height above mean sea level. WGS84 ellipsoidal height has a different reference surface. GPSDeck keeps these values separate; ECEF and 3D geometry use valid ellipsoidal height. Missing height is not replaced by zero.
The difference between the two heights in a valid, single location sample is a system-derived geoid separation. It does not identify which geoid model Apple used.
Accuracy and limits
Horizontal accuracy is the system's reported radius, not a complete covariance matrix or a guaranteed 95% confidence region. More coordinate digits do not make a location more accurate.
Distance and bearing use WGS84 ellipsoidal calculations. A conversion or distance may be unavailable when inputs are invalid or the computation does not converge. Grid choices and precision affect how a position is represented.
Use independent references when a task requires certified surveying, safety-critical navigation or a legally defined datum. GPSDeck does not provide those certifications.
For operational questions, see Support.