What inputs does UTM to lat/long need?

It needs the zone number (1 to 60), the hemisphere (north or south), the easting in metres and the northing in metres. The hemisphere is required because northings repeat between the two halves of the globe.

Why does the hemisphere matter so much?

In the southern hemisphere a false northing of 10000000 metres is added so values stay positive. Without knowing the hemisphere, the converter cannot tell whether a northing of 5000000 means the north or south half.

What ellipsoid is assumed?

The WGS-84 ellipsoid is used, matching GPS and most modern datasets: semi-major axis 6378137 metres and flattening 1/298.257223563.

How accurate is the inverse projection?

The Krüger series used here is accurate to sub-millimetre level inside the zone, so the recovered latitude and longitude match the original coordinates to well under a metre.

What is the UTM to Lat/Lng Converter?

Convert Universal Transverse Mercator (UTM) coordinates back to WGS-84 decimal latitude and longitude. Enter the zone, hemisphere, easting and northing in metres and get precise geographic coordinates using the inverse transverse Mercator projection. It runs free in your browser on Gera Tools, with nothing uploaded.

UTM to Lat/Lng Converter

Name: UTM to Lat/Lng Converter
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

This tool converts UTM coordinates — zone, easting and northing — back to WGS-84 decimal latitude and longitude. It is the inverse of the lat/long to UTM projection and is useful when a dataset, survey or map gives you metre-based grid references that you need as GPS coordinates.

How it works

The easting has its false easting of 500000 m removed, and in the southern hemisphere the false northing of 10000000 m is subtracted from the northing. The values are divided by the meridian-arc radius and the central-meridian scale factor k0 = 0.9996, then a Krüger inverse series in the conformal coordinates recovers the latitude and longitude offset from the zone’s central meridian:

central meridian = (zone - 1) * 6 - 180 + 3 degrees
longitude = central meridian + recovered offset

The series runs on the WGS-84 ellipsoid, so the result matches GPS coordinates directly.

Where UTM coordinates appear in practice

UTM is the coordinate system behind a large share of professional geographic data. Common places you encounter UTM values include:

Survey data and engineering drawings. Land surveys in many countries provide control points as UTM easting/northing values, since metres are easier to work with at construction scale than degrees.
Military grid reference system (MGRS). MGRS is derived from UTM and uses the same underlying zone structure. Understanding UTM helps decode MGRS references.
GIS data exports. Many GIS tools and spatial databases can export coordinate layers in UTM projection. When someone hands you a CSV with columns named “Easting” and “Northing” along with a zone number, this converter returns them to decimal degrees.
Remote sensing and aerial imagery. Satellite imagery metadata and orthophotos often carry bounding coordinates in the UTM zone of the scene.
Environmental and ecological field data. Researchers recording wildlife sightings, soil samples, or water quality measurements in the field often use handheld GPS units that can output UTM.

Understanding the zone structure

The world is divided into 60 UTM zones numbered 1 to 60, each spanning 6 degrees of longitude. Zone 1 covers 180°W to 174°W; zone 60 covers 174°E to 180°E. Within a zone, easting is measured in metres from the central meridian, with a false easting of 500,000 m added so all values are positive. Northing is measured from the equator, with no offset in the northern hemisphere and a 10,000,000 m false northing in the southern hemisphere.

This means a valid easting is always between roughly 100,000 m and 900,000 m from the zone’s central meridian — if your easting is far outside that range, you likely have an error in the zone number or the value itself.

Common mistakes to avoid

Wrong hemisphere. A northing of 5,500,000 could be about 50°N in the northern hemisphere or about 41°S in the southern hemisphere. Get the hemisphere wrong and the latitude will be off by tens of degrees.
Confusing Easting and Northing. Easting is the east-west distance and Northing is the north-south distance. They are sometimes swapped in spreadsheets that list columns in the reverse order.
Using the wrong zone. A coordinate that sits near a zone boundary may have been assigned to either of the neighboring zones. If the result looks like it should be in the UK but lands in the Atlantic, the zone number is probably off by one.

Tips

Always set the correct hemisphere — a southern-hemisphere northing looks identical to a northern one without it. UTM is valid only between about 80°S and 84°N. The inverse series is accurate to sub-millimetre level inside a zone, so round-tripping a coordinate through both converters returns the original value. Everything runs in your browser.