How the calculation works
The formulas
Enter inside dimensions. For an L shape, remove a corner notch from the outer rectangle. For extra sections, set each rectangle’s X/Y offset from the same origin; shared edges disappear from the perimeter.
Rectangle: A = L × W; V = A × H
L shape: A = L × W − notchL × notchW
Combined: A = union(rectangles); P = external boundary length
Assumptions to check
- One ceiling height applies to every section; rectangles are axis aligned.
- Coordinates may be negative. Disconnected sections include each separate outer boundary.
A worked example
A 5 × 4 m room with a 2 × 1.5 m corner notch has 17 m² of floor, 18 m of perimeter, and 45.9 m³ at a 2.7 m height.