Latitude and longitude to UTM
UTM splits the world into 60 zones, each 6 degrees of longitude wide, and flattens each zone with a Transverse Mercator projection. Enter a position to get its zone, easting, and northing, and see how the map’s scale error grows as you move away from the zone’s central meridian.
Position
Places to try
Scale factor k across this zone at this latitude. Below 1 the map is shorter than the ground; above 1 it is longer. The red dot is your point.
The 60 zones, each 6 degrees of longitude wide. Yours is highlighted.
Try this
- Start at Lake Union Park, then drag the longitude slider west toward the zone edge. Watch the red dot climb the curve: k passes 1 about 180 km from the central meridian.
- Try Zone edge, equator. The map is about 1 meter too long per kilometer there. Over a 10 m robot path that is 1 cm: small, but it adds up across a big survey.
- Read the note at the bottom: the same point in the next zone has an easting hundreds of kilometers different. Never mix zones in one map.
- Try Norway exception: by plain arithmetic this point would be in zone 31, but zone 32 is widened there.
Notebook
Work with the same script in cells, like Jupyter, right here in the browser. Edit any cell and run it. Nothing is saved: Reset brings a cell back, and Download .ipynb keeps your edited version for VS Code or Jupyter.
The Python script: latlon_utm.py
This is the script the page runs. Run it yourself with python3 latlon_utm.py.