Coordinate Converter

Four ways to write the same point

Decimal degrees are what GPS receivers and web maps use: one number for latitude, one for longitude, with south and west negative. Degrees, minutes and seconds are the older written form, the one on paper maps and in property deeds: each degree splits into 60 minutes, each minute into 60 seconds, and a letter says which hemisphere. UTM cuts the world into 60 zones, each 6 degrees of longitude wide, and measures metres east and north inside the zone, which is why surveyors and rescue teams prefer it: distances on the ground read straight off the numbers. MGRS is the military shorthand for UTM: the zone and a latitude band letter, then two letters naming a 100 km square, then the metres inside that square, compact enough to read over a radio.

The conversions are exact in the mathematical sense and approximate in the practical sense. The earth is modelled as the WGS84 ellipsoid, a smooth mathematical shape, while the real ground is lumpy; the projection maths is accurate to well under a metre inside a zone, but a point near a zone edge belongs to the neighbouring zone's map just as well, and a coordinate from a different datum can be off by hundreds of metres. When a conversion matters for navigation, check the result on a map you trust before you walk to it.