Calculate great-circle distance between two coordinates, or total length/area from a GeoJSON file. Free, private, no upload to server.
The Haversine formula, which computes great-circle distance between two points on a sphere. It's accurate to within about 0.5% of the WGS84 ellipsoid model, which is standard for most mapping and navigation use cases.
A spherical excess formula that sums longitude differences weighted by the sine of latitude across the polygon's vertices, the same approach used by libraries like Turf.js. Polygon holes are subtracted from the outer ring automatically.
LineString and MultiLineString give a total length. Polygon and MultiPolygon give a total area (holes subtracted). Upload a FeatureCollection to measure every feature at once.
Yes, completely. All calculation happens inside your browser using JavaScript. Nothing is uploaded to a server.
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