Geometry Tool
Area Calculator — square, circle, triangle, polygon & irregular shapes.
Calculate the area of any 2D shape — square, rectangle, circle, ellipse, triangle, regular polygon, or custom irregular shape using the shoelace theorem. Auto-converts to sq ft, sq in, sq yd, sq m, and acres.
Area Calculator
Side Length (ft)
Length (ft)
Width (ft)
Radius (ft)
Semi-axis A (ft)
Semi-axis B (ft)
Enter all 3 side lengths (Heron's formula)
Side A (ft)
Side B (ft)
Side C (ft)
Regular polygon — all sides equal length
Number of Sides
Side Length (ft)
Enter X/Y coordinates of each vertex (Shoelace theorem)