UTM Converter — UTM ↔ Latitude/Longitude

The Universal Transverse Mercator system divides the world into 60 north–south zones, each 6° of longitude wide, and projects each zone onto a flat grid measured in metres. A UTM coordinate has a zone number (1–60), a hemisphere or latitude band letter, an easting (metres east within the zone), and a northing (metres north of the equator, or of a false origin in the south). Because it is metric and locally flat, UTM makes distance and area calculations simple — which is why surveying, GIS, and military mapping use it.

Easting is the distance in metres east of the zone's central meridian, which is assigned a false easting of 500,000 m so values never go negative. Northing is metres north of the equator in the northern hemisphere; in the southern hemisphere the equator is assigned 10,000,000 m and northings count up towards it from the south.

That is the MGRS latitude band letter — bands lettered C to X (skipping I and O) cover 8° of latitude each from 80°S to 84°N. It tells you roughly how far north or south you are. For conversion purposes what matters is the hemisphere: bands N and later are the northern hemisphere, bands C through M the southern.

It uses the Krüger series expansion of the transverse Mercator projection on the WGS84 ellipsoid — the same mathematics behind professional GIS libraries — and is accurate to well under a metre everywhere UTM is defined. Note that coordinates from an old paper map may be on a different datum (such as NAD27 or ED50), which can differ from WGS84 by up to a few hundred metres.

UTM is defined from 80°S to 84°N. Poleward of that, the distortion of a transverse Mercator projection becomes unacceptable, so the Universal Polar Stereographic (UPS) grid is used instead. If you enter a latitude beyond the limits, the tool tells you rather than returning a misleading number.