Bounding Box Calculator
Generate a latitude/longitude bounding box from a center point and a radius. Outputs all four corners, the bbox array, and a GeoJSON polygon — ready to paste into a spatial query. Free, runs in your browser.
Using the bounding box
The output is given in three forms, all in [longitude, latitude] order to match GeoJSON and most mapping APIs:
- bbox array —
[minLng, minLat, maxLng, maxLat]. Pass this as thebboxparameter to Mapbox, OSM Overpass, PostGIS&&queries, etc. - Four corners — useful for plotting or CSV export.
- GeoJSON polygon — a closed 5-point ring ready for any GeoJSON consumer.
Frequently Asked Questions
What is a bounding box?
A bounding box (bbox) is the smallest rectangle (in latitude/longitude) that contains an area of interest. It is defined by four numbers: [minLng, minLat, maxLng, maxLat]. Bounding boxes are the standard way to query spatial databases, tile servers, and mapping APIs for "everything in this region".
How is the bounding box calculated from a center and radius?
For a sphere of radius 6371 km, we add/subtract the angular offset Δ = radius / 6371000 radians to the latitude. For longitude, we divide by cos(latitude) to account for meridian convergence: Δlng = Δlat / cos(lat). The result is accurate to within a few metres for radii up to ~1000 km.
Why is my longitude span wider than my latitude span?
Because lines of longitude converge toward the poles. At higher latitudes, a given east-west distance corresponds to more degrees of longitude, so the bbox gets "stretched" east-west. At the equator (lat=0) the spans are equal; at lat=60° the longitude span is double the latitude span for the same radius.
What format should I use to query an API?
Most mapping APIs (Mapbox, OSM, PostGIS) accept bbox=minLng,minLat,maxLng,maxLat — note longitude first. GeoJSON follows the same order. Some older APIs use lat-first; always check the docs.