How to find the square footage of an irregular shape
To find the square footage of an irregular shape, divide the composite shape into rectangles, calculate each rectangle's area with length × width, then add the sections. The Irregular Shape Area Calculator totals those sections in square feet (ft²) and square meters (m²).
Sketch the outline first and draw dividing lines at inside corners. Measure every length and width in the same unit, usually feet. Enter each rectangle as its own section, or use the multiple rooms inputs to add named sections in one pass.
This method covers odd-shaped rooms, L-shaped plans, and other composite floor plans that do not fit a single rectangle.
Example: an L-shaped room
An L-shaped room divides into two rectangles. A 12 × 10 ft rectangle is 120 square feet. An 8 × 6 ft rectangle is 48 square feet. Add them for 168 square feet total.
Measure each arm of the L from wall to wall. Do not count the overlapping corner twice. Apply the same split-and-add steps to any odd-shaped room made of rectangular sections.
Irregular shapes with triangles or curves
Triangular sections use half the base times the height (½ × base × height). Curved edges can be approximated with a circle or semicircle, or with short straight segments that form trapezoids along the curve.
Open the triangle calculator for base-and-height or three-side (Heron) triangles. Open the circle calculator for round bays or circular pads. Add those areas to the rectangular total for the full irregular shape.
Convert to square meters
To convert an irregular shape's square footage to square meters, multiply by 0.0929. A 168-square-foot L-shaped room equals 15.6 square meters.
A 168-square-foot irregular room equals 15.6 square meters (m²).
Use the square yards calculator for any area.
For square yards, divide square feet by 9, or use the square yards calculator.
Irregular shape area calculator summary
The Irregular Shape Area Calculator finds the square footage of an irregular or odd-shaped room by dividing the plan into rectangles and triangles, then adding the section areas. An L-shaped example of 12 × 10 plus 8 × 6 totals 168 square feet.
Convert the total with × 0.0929 for square meters. Use the uneven sides tool when the problem is a four-sided lot that needs a diagonal.