Maths & numbers

Convex hull builder

Find and plot the outer boundary of a point cloud.

Convex hull builder
Esc to restore

Your inputs

Use exact X,Y headings, without repeating the first point unless closing a polygon.

Up to 25 MB per file, 50,000 data rows, 200 columns and 2 million data cells. Fully blank rows and columns are ignored before row, column and cell limits are checked. Individual tools may have smaller result or chart limits.

Results update as you type. Larger files run when you press Update result.

Processed on your device

Your result

LOCAL & PRIVATE

Your result will appear here.

Your inputs stay in this browser. Nothing is uploaded or saved.

A clear answer. Here’s how.

Uses Andrew’s monotone-chain hull after sorting and removing exact duplicate coordinates. Supports 2–1,000 points within ±1 billion. Collinear interior points are omitted; a collinear cloud returns its two extreme endpoints and zero area. Exported vertices are counter-clockwise for a non-degenerate hull, with implicit closure. A coordinate plot accompanies the table; floating-point orientation tests can be sensitive for nearly collinear points.

See a worked example

Worked example

A fixed demonstration, separate from the values you enter above.

Point CSV
X,Y
0,0
4,0
4,3
0,3
2,1

Example result

Example result
VertexXY
100
240
343
403

4 boundary vertices; area 12. Collinear interior points and duplicate coordinates are omitted. The hull closes from its last vertex to its first.

Keep going.

Percentage calculatorClosest pair in a point cloudPolygon centroid calculatorPoint-in-polygon checker