Bounding-box calculator
Compute the min/max lat/lon bounding box around a set of points. Runs on your device.
Runs on your device. The file is never uploaded.
Bounding-box calculator takes semicolon-separated lat,lon pairs and prints the minimum and maximum of each axis, a GeoJSON bbox array and the centre. That array runs minLon, minLat, maxLon, maxLat, the reverse of the pairs you type. A plain minimum and maximum cannot cross the antimeridian, so 179 and -179 give a box spanning almost the world.
Questions
How do I enter the points?
As "lat,lon" pairs separated by semicolons, for example 40.7128,-74.0060; 51.5074,-0.1278. Spaces around the pairs and around the comma are trimmed. Latitude comes first, which is the opposite order to GeoJSON coordinates, and the tool prints a GeoJSON bbox for you so you never have to swap them by hand.
What does it give me back?
Six lines: min lat, max lat, min lon, max lon, a GeoJSON bbox array in the order [minLon, minLat, maxLon, maxLat], and the center as lat, lon. The center is the midpoint of the box, not the average of your points, so one distant outlier moves the box but does not pull the center toward the cluster.
Does it handle a box that crosses the antimeridian?
No. It takes a plain minimum and maximum of the numbers you give it, so a point at 179 and one at -179 produce a box spanning almost the whole world rather than the two-degree strip between them. Split your points either side of 180 and compute two boxes if you need that case.
What if I give it one point?
You get a zero-size box: the minimum and maximum match on both axes, and the center is the point itself. That is valid, if not much use. Two points give the box that contains both, which is the smallest case worth running. An empty list is refused with "need at least 1 point".
Why did it reject one of my pairs?
A pair that does not yield two finite numbers is quoted back to you as not a valid "lat,lon" pair. Common causes are a missing longitude, a semicolon used inside a pair instead of a comma, or a degree symbol left in the value. Ranges are not checked, so a latitude of 200 is accepted as a number.
Do my coordinates leave the page?
No. The points stay in this tab. The calculation is a minimum and a maximum over the numbers you typed, run in a Web Worker, with no request and nothing stored. Coordinates are often the sensitive part of a dataset, which is why it is worth saying plainly.