How is the UTM zone determined?

The world is divided into 60 longitude zones, each 6 degrees wide. The zone number is floor((longitude + 180) / 6) + 1, giving zone 1 starting at 180 degrees west. A few exceptions exist around Norway and Svalbard.

What ellipsoid does this converter use?

It uses the WGS-84 ellipsoid with semi-major axis 6378137 metres and flattening 1/298.257223563, the global standard used by GPS. Easting and northing are in metres.

What is the false easting and false northing?

Each zone uses a false easting of 500000 metres so eastings are always positive. In the southern hemisphere a false northing of 10000000 metres is added so northings stay positive there too.

How accurate is the projection?

The transverse Mercator series used here is accurate to well under a millimetre within a UTM zone, far beyond any practical surveying need. Accuracy degrades only far outside the zone's 6-degree band.

Lat/Lng to UTM Converter

This tool converts WGS-84 latitude and longitude to UTM — Universal Transverse Mercator — coordinates, the metre-based grid system used by topographic maps, militaries and GIS worldwide. It returns the zone number, the hemisphere, and the easting and northing in metres.

How it works

UTM divides the globe into 60 zones, each 6° of longitude wide. The zone number is:

zone = floor((longitude + 180) / 6) + 1

Within a zone, the point is projected with a transverse Mercator projection on the WGS-84 ellipsoid, scaled by the central-meridian scale factor k0 = 0.9996. The math evaluates a Karney-style series in the conformal latitude, then adds a false easting of 500000 m so eastings are positive, and (in the southern hemisphere) a false northing of 10000000 m so northings are positive there too.

Tips and notes

UTM is only valid between roughly 80°S and 84°N; beyond that the UPS polar system is used instead. Eastings near the zone edge can exceed the nominal range, which is normal. The full ellipsoidal series is accurate to sub-millimetre level inside a zone. Everything runs in your browser. To reverse the calculation, use the UTM to Lat/Lng converter.