Point in Polygon
Ray-casting point-in-polygon test
About this calculator
The Point in Polygon Calculator tests whether a point lies inside, outside, or on the boundary of any polygon using the ray-casting (even–odd) algorithm. It handles convex and concave polygons, detects points exactly on an edge or vertex, and visualizes the ray and its edge crossings.
How to use the Point in Polygon calculator
- Enter the measurements you know into the input fields.
- Read the computed properties — they update instantly as you type.
- Compare the diagram with your figure to confirm the setup is right.
- Copy the page URL to share the exact calculation.
Common examples
- Square 0,0 6,0 6,4 0,4 with point (2,3) → inside (1 crossing)
- Square 0,0 6,0 6,4 0,4 with point (10,3) → outside (0 crossings)
- Point (6,2) on the right edge of that square → on boundary
- L-shape 0,0 4,0 4,2 2,2 2,4 0,4 with point (3,3) → outside (in the notch)
Frequently asked questions
How does the Point in Polygon calculator work?
Enter the known measurements of your figure and the calculator applies the standard geometric formulas to find the remaining properties, alongside a diagram that reflects your numbers. All values are computed with high-precision arithmetic.
When would I use the Point in Polygon calculator?
It helps with geometry homework, technical drawing, construction and DIY layout, and any situation where you know some measurements of a shape and need the rest.
How accurate are the results?
Formulas are evaluated at 30 significant digits of precision internally, including roots and trigonometric functions. Displayed values are rounded for readability, but the underlying computation does not accumulate floating-point drift.
Can I share a specific calculation with someone else?
Yes. Every value you enter updates the URL, so copying the address bar and sharing the link reopens the exact same figure and results for whoever clicks it.