Points to Polygon Generator: Wrap a Boundary Around Your Coordinates
This free online tool takes any set of points and wraps a boundary polygon around them – no GIS software required. Upload a GeoJSON or KML file of GPS waypoints, survey coordinates, or any point data, and instantly generate either a convex outer boundary or a concave tight-fit polygon that follows the shape of your point cluster. Download the result as GeoJSON or KML.
Point to Polygon Boundary Generator
Upload your points or paste GeoJSON below, then choose your boundary type and click Generate.
How to Use This Tool
Loading Your Points
There are two ways to load your data:
- Drag and drop a GeoJSON or KML file directly onto the upload area, or click it to browse your files
- Paste GeoJSON into the text area and click Load
The tool accepts any GeoJSON geometry type – a FeatureCollection of Points is the most common input, but it will also extract coordinates from LineStrings, Polygons, or mixed collections. KML files exported from Google Earth, Google My Maps, or any GIS application are supported directly.
Choosing a Boundary Type
Two boundary modes are available:
- Convex (outer wrap) – draws the smallest possible polygon that fully encloses all points with no indentations. Think of it like stretching a rubber band around your points. Every point is inside or on the boundary, and the shape is always a simple convex polygon with no concave edges.
- Concave (tight fit) – follows the actual shape of your point cluster more closely, pulling inward where points are sparse. Use the Max Edge Distance slider to control how tightly the boundary hugs the points: a smaller value produces a tighter, more detailed boundary, while a larger value relaxes it towards the convex shape.
Downloading the Result
Once the boundary is generated, use the Save buttons to download:
- Save GeoJSON – standard GeoJSON format compatible with QGIS, Mapbox, Felt, and most web mapping tools
- Save KML – opens directly in Google Earth and Google My Maps
You can also download your original input points in either format.
What Is a Convex Hull?
A convex hull is the mathematical term for the smallest convex polygon that contains a set of points. In practical terms it is the boundary you would get by stretching a rubber band around your points and letting it snap tight. Every point lies inside or on the boundary, and the polygon has no inward-facing edges.
Convex hulls are widely used in GIS for:
- Estimating the geographic extent of a dataset
- Creating rough service area or study zone boundaries
- Detecting outlier points that fall far outside the main cluster
- Simplifying complex point distributions into a single polygon for overlay analysis
What Is a Concave Hull?
A concave hull, sometimes called an alpha shape, is a more detailed boundary that follows the actual shape of a point cluster rather than just wrapping around its outermost extent. Where a convex hull ignores gaps and indentations, a concave hull can produce a boundary that reflects irregular cluster shapes – useful when your points form an L-shape, a ring, or multiple lobes.
The Max Edge Distance parameter controls the level of detail. A small value (e.g. 5 km) means no two points more than 5 km apart can share a boundary edge, producing a tighter shape. Increase it if the boundary breaks into disconnected pieces.
Common Use Cases
- GPS track extents – wrap a boundary around waypoints recorded during a field survey or outdoor activity
- Wildlife tracking – define a home range polygon from animal GPS collar data
- Customer distribution – draw a service area boundary around a set of customer locations
- Incident mapping – define the extent of a cluster of reported events or observations
- Survey plot boundary – generate an outline from sample point coordinates
- Study area delineation – quickly create a boundary polygon from field sample locations
Supported File Formats
GeoJSON Input
Paste or upload any valid GeoJSON. The tool accepts Point, MultiPoint, LineString, Polygon, Feature, and FeatureCollection types. All coordinate vertices are extracted and used as input points, so you can wrap a boundary around the vertices of an existing polygon or the nodes of a line network.
KML Input
Upload .kml files exported from Google Earth, Google My Maps, QGIS, ArcGIS, or any other GIS application. The tool converts KML to GeoJSON automatically before processing.
Output Formats
Results can be saved as GeoJSON (.geojson) or KML (.kml). GeoJSON is the best choice for use in web mapping tools, QGIS, or further processing. KML is ideal if you want to open the boundary in Google Earth or share it via Google My Maps.
Frequently Asked Questions
What is the difference between convex and concave hull?
A convex hull is the tightest simple polygon that fully contains all your points with no inward edges – like a rubber band around pins. A concave hull follows the actual shape of your point distribution, creating a more detailed boundary that can have indentations and follow the natural outline of your data.
My concave boundary breaks into separate pieces – what should I do?
This happens when the Max Edge Distance is set too small. Increase the slider value until the boundary forms a single connected polygon. If your points form genuinely separate clusters a convex hull may be more useful.
Can I use this with CSV or spreadsheet coordinate data?
Not directly, but you can convert a CSV of latitude/longitude coordinates to GeoJSON first using a tool like the MapScaping GeoJSON viewer, then paste or upload the result here.
Does it work with KML from Google Earth?
Yes. Export your placemarks or path from Google Earth as a .kml file and drag it into the upload area. The tool reads the geometry and extracts all coordinate vertices automatically.
How accurate is the area calculation?
Areas are calculated using Turf.js with an ellipsoidal model based on the WGS84 reference ellipsoid, which gives results accurate to within a fraction of a percent for typical polygon sizes.
Is my data sent to a server?
No. All processing happens in your browser. Your coordinates are never uploaded anywhere. Closing the tab clears everything.
How many points can it handle?
The tool works well with thousands of points. Very large datasets (tens of thousands of points) may be slower to render on the map but the boundary calculation itself is fast.
[Continuar leyendo en Mapscaping](https://mapscaping.com/points-to-polygon-wrap-a-boundary-around-coordinates/) ### Contexto para la comunidad GIS Esta información es relevante para profesionales de geoprocesamiento, analistas espaciales y usuarios de herramientas como QGIS, ArcGIS y PostGIS.