Frequently Asked Questions
Everything you need to know about the Polygon Angle Calculator.
How do I find the sum of interior angles?
Use (n−2)×180°, where n is the number of sides — this calculator does it instantly.
How do I find one interior angle of a regular polygon?
Divide the sum by n: (n−2)×180°/n.
What's the sum of exterior angles?
Always 360°, regardless of the number of sides, for any convex polygon.
Can I work backwards from an angle to find the number of sides?
Yes, enter a known interior or exterior angle and it solves for n.
What if the angle doesn't match a whole-sided polygon?
The calculator flags this clearly rather than showing a fractional, meaningless number of sides.
Does it name the polygon?
Yes, common polygons (triangle through decagon) are named automatically based on n.
Does this work for irregular polygons?
The angle sum formulas apply to any polygon, but the per-angle values assume a regular (equal-angle) polygon.
Does it show a diagram?
Yes, a scaled polygon with n sides is drawn.
Is it free?
Completely free, no sign-up or limits.
Does it work on mobile?
Yes, fully responsive.