Coordinate Conversion Calculator
Convert between geographic coordinates (latitude/longitude) and UTM (Universal Transverse Mercator) using WGS84 datum.
About this calculator
This calculator converts between decimal-degree latitude/longitude and UTM easting/northing on the WGS84 ellipsoid, using the Conversion Direction select to switch between two entirely separate code paths rather than one shared formula. When converting Lat/Lon to UTM, only Latitude and Longitude feed the math -- the UTM Easting, Northing, and Zone fields are only used going the other direction, so they have zero effect on the result in this mode, and vice versa: converting UTM to Lat/Lon uses only the UTM Easting, Northing, and Zone fields, ignoring whatever Latitude and Longitude are currently set to. Within the Lat/Lon-to-UTM direction, Easting is driven mainly by Longitude's distance from the UTM zone's central meridian, while Northing is driven mainly by Latitude -- but the transverse Mercator projection couples the two coordinates, so Latitude also has a smaller cross-term effect on Easting and Longitude has a smaller cross-term effect on Northing; neither is ever fully independent of the other input.
Similarly, in the UTM-to-Lat/Lon direction, the UTM Zone number is used to place the zone's central meridian for computing Longitude, but it plays no role in computing the resulting Latitude value, which comes entirely from the Northing coordinate. This tool implements the transverse Mercator series expansion published by John P. Snyder in USGS Professional Paper 1395, "Map Projections: A Working Manual" -- the standard reference formula USGS itself uses for its own topographic map projections -- on the WGS84 ellipsoid; it is accurate to within a few centimeters for typical civilian surveying use but is not a substitute for a geodetic-grade tool for legal boundary work.
Inputs
Results
UTM Easting
500,000 m
≈ 12 marathons
UTM Northing
4,427,757.22 m
≈ 105 marathons
Figures current as of 1987. Source: Snyder, J.P., Map Projections: A Working Manual, U.S. Geological Survey Professional Paper 1395, 1987 (Transverse Mercator Projection, Forward and Inverse Formulas for the Ellipsoid)
How to Use This Calculator
- Select the Conversion Direction: Lat/Lon → UTM or UTM → Lat/Lon.
- For Lat/Lon → UTM, enter the Latitude and Longitude in decimal degrees.
- For UTM → Lat/Lon, enter the UTM Easting, Northing, and Zone.
- Review the converted Latitude and Longitude (in decimal degrees and DMS) or the converted UTM Easting, Northing, and Zone.
- All conversions use the WGS84 datum.
How the result changes with Longitude
| Longitude | UTM Easting | UTM Northing |
|---|---|---|
| -180 | 243,900.35 m | 4,432,069.06 m |
| -157 | 670,725.49 m | 4,429,672.97 m |
| -79 | 670,725.49 m | 4,429,672.97 m |
| -52 | 414,639.54 m | 4,428,236.06 m |
What each input means
- Conversion Direction
- Select the conversion direction.
- Latitude
- Latitude in decimal degrees (positive = North, negative = South).
- Longitude
- Longitude in decimal degrees (positive = East, negative = West).
- UTM Easting
- UTM easting coordinate in meters.
- UTM Northing
- UTM northing coordinate in meters.
- UTM Zone
- UTM zone number (1-60).
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersConversion Direction = 1, Latitude = 40, Longitude = -105, UTM Easting = 500000 = 6 input(s) provided
- Calculate UTM EastingUTM Easting500000 = 500000
- Calculate UTM NorthingUTM Northing4427757.22 = 4427757.22
- Calculate LatitudeLatitude40 = 40
- Calculate LongitudeLongitude-105 = -105
Figures and sources
- Transverse Mercator forward and inverse series expansion on the WGS84 ellipsoid (1987) — Snyder, J.P., Map Projections: A Working Manual, U.S. Geological Survey Professional Paper 1395, 1987 (Transverse Mercator Projection, Forward and Inverse Formulas for the Ellipsoid)
Engine last updated . Checked against 3 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
Why doesn't entering a UTM Zone change anything when I convert Lat/Lon to UTM?
The UTM Zone, Easting, and Northing fields are only used by the UTM-to-Lat/Lon conversion path. When Conversion Direction is set to Lat/Lon to UTM, the calculator determines the zone automatically from your Longitude and ignores whatever value is sitting in the UTM Zone field.
Does Latitude affect the resulting UTM Easting value?
Mostly indirectly -- Easting is driven primarily by how far your Longitude sits from the UTM zone's central meridian, while Latitude is the primary driver of the resulting Northing. But the transverse Mercator projection couples the two: Latitude does have a smaller secondary effect on Easting (and Longitude a smaller secondary effect on Northing), so neither output coordinate depends on only one input coordinate.
What formula does this calculator use for the projection math?
The transverse Mercator forward and inverse series expansion published by John P. Snyder in USGS Professional Paper 1395, "Map Projections: A Working Manual" -- the same reference formula the U.S. Geological Survey uses for its own topographic quadrangle maps -- applied on the WGS84 ellipsoid. It is the standard closed-form approximation used throughout civilian GIS and surveying software, accurate to within a few centimeters at typical UTM zone widths.
When converting UTM back to Lat/Lon, does the Zone number affect the resulting Latitude?
No -- the resulting Latitude is computed entirely from your UTM Northing value using the WGS84 meridional arc formula. UTM Zone only supplies the central meridian longitude used to compute the resulting Longitude, so it has no bearing on the Latitude result.
Why does the calculator ask for both sets of coordinate fields if only one direction is used at a time?
Conversion Direction switches between two completely independent formulas rather than one shared calculation, so the fields relevant to the direction you did not choose stay visible but inert. This lets you flip between directions without re-entering the coordinates you already typed for the other mode.
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