How are areas and distances calculated?
The tool converts input coordinates to longitude/latitude WGS84 and uses Turf.js to calculate geodesic-style area and path length. Outputs include square metres, hectares, perimeter, centroid and bounding boxes. The preview is drawn locally without a third-party map service.
Belgian Lambert support
EPSG:4326, EPSG:31370 and EPSG:3812 are supported using the existing GratisTools coordinate converter. The CRS selector overrides GeoJSON metadata; standard GeoJSON without explicit CRS is assumed to be WGS84. Choose the actual CRS before analysis. KML coordinates always use WGS84.
Buffers, intersection and export
Buffers are approximate distance zones. Polygon intersections only work with compatible valid geometries; invalid rings can cause failures. Download JSON and CSV measurements or the resulting geometry as WGS84 GeoJSON.
FAQ
Is this suitable for cadastral measurements?
No. Approximate transforms and spherical calculations do not replace professional land surveying or official cadastral data.
Are my files uploaded?
No. GIS measurements run with JavaScript and WebAssembly running in your browser tab. Your files are read from your device and the results are created on your device; nothing is sent to gratistools.be or anyone else, which is also why there are no queues, daily limits or watermarks. See the privacy page.
Frequently asked questions
Is this tool free?
Yes. The core tool is free to use in your browser.