How the estimate works
Rectangle: L × W. Square: side². Triangle: Heron’s formula √[s(s−a)(s−b)(s−c)] using its three side lengths. Circle: π × radius².
Assumptions and limits
Shapes are idealized; irregular rooms may need to be split into smaller shapes and summed.
Example
A 4 m × 3 m rectangle has an area of 12 m² and perimeter of 14 m.