How it works
Choose a shape, enter the measurements in feet or meters, and get the area in square feet along with square meters, square yards and acres.
For an L-shaped room, split it into two rectangles that do not overlap: measure the full length and width of one leg, then the remaining part of the other leg. Add the areas. Any irregular room can be broken into rectangles and triangles the same way.
For real estate, finished square footage is usually measured from the exterior walls and excludes garages and unfinished basements. For flooring or paint, measure inside the walls.
Formula
Rectangle = L × W. L-shape = L₁ × W₁ + L₂ × W₂. Circle = π × (d ÷ 2)². Triangle = ½ × base × height. 1 m² = 10.764 sq ft; 1 acre = 43,560 sq ft.
Questions people ask
How do I calculate square footage of an L-shaped room?
Divide it into two rectangles, multiply length by width for each, and add them. For example, 20 × 10 plus 10 × 10 gives 300 sq ft.
How many square feet are in an acre?
43,560 square feet. A quarter-acre lot is 10,890 sq ft.
How do I convert square meters to square feet?
Multiply by 10.764. A 20 m² room is about 215 sq ft.
What if my measurements are in feet and inches?
Convert inches to decimal feet by dividing by 12. Twelve feet 6 inches is 12.5 ft.