Select a shape and enter the required dimensions to see the results here.
FAQ
Which shapes can I calculate?
The tool covers rectangles, circles, triangles, trapezoids, and regular polygons. Enter the dimensions requested for each shape to get area and perimeter.
Do I need to specify units?
Use whatever units you prefer. The calculator keeps everything consistent, so if you enter centimetres the area will be in square centimetres and the perimeter in centimetres.
What do I enter for a regular polygon?
Provide the number of sides (3 or more) plus at least one of the following: side length, circumradius, or apothem. Missing values are derived automatically.