How it works
The tool reads your text, works out the format, and joins the points in order. For a closed area it computes the polygon’s area on a sphere of radius 6,371,000 m by adding the spherical excess of the triangles fanned out from the first corner; the perimeter is the sum of great-circle (haversine) distances between consecutive corners, plus the closing side. These are the same formulas, with the same Earth radius, as the Land Measure app — so the same corners give the same numbers here and on your phone.
Why not the familiar shoelace formula? Degrees of longitude shrink toward the poles, so treating latitude and longitude as flat x/y numbers distorts the shape. The spherical method needs no projection and works anywhere, including plots that cross the 180° meridian. Our guide how to calculate area from GPS coordinates compares the methods in detail.
Accepted input
| Format | Example | Order |
|---|---|---|
| List (decimal degrees) | 41.88, -93.62 | lat, lon |
| List (DMS / DMM) | 41°52′48″N, 93°37′12″W | lat, lon |
| CSV with header | name,latitude,longitude | by column name |
| KML | <coordinates>-93.62,41.88,0 … | lon,lat[,alt] |
| GPX | <trkpt lat="41.88" lon="-93.62"> | attributes |
| GeoJSON | [[-93.62, 41.88], …] | [lon, lat] |
Polygons with holes are measured by their outer boundary only, and the tool says so. For the differences between these formats, see KML vs GPX vs GeoJSON. To convert a single coordinate between notations, use the coordinate converter.
Worked example
The example (press Load example) is a field near Ames, Iowa with corners at 41.88000, −93.62000 · 41.88000, −93.61400 · 41.87550, −93.61400 · 41.87550, −93.62000. Its area is 248,565 m² = 24.86 ha = 61.42 acres and its perimeter 1,994.26 m. The north and south sides are about 496.7 m long, the east and west sides about 500.4 m.