Calculate the exact area of any room, yard, or roof. Select your shape below to get started.
Break your L-shape into two separate rectangles (Area 1 and Area 2).
Calculating square footage is the critical first step for almost every home improvement project. Whether you are laying hardwood, painting a bedroom, or pouring a concrete patio, knowing your exact area prevents you from buying too little material (which causes dye-lot mismatches) or wasting money on excess supplies.
For a standard rectangular room, the formula is simple: Length Γ Width = Square Footage. For example, a bedroom that is 12 feet long and 10 feet wide is exactly 120 square feet.
Real houses aren't perfect boxes. Here is how contractors calculate square footage for complex spaces:
Open-concept living rooms and kitchen additions often form an "L". To calculate this, divide the room into two separate rectangles. Calculate the square footage of Rectangle A, calculate the square footage of Rectangle B, and simply add them together.
If you are calculating the square footage of a triangular roof gable for painting, or a corner garden bed for mulch, use the triangle formula: 0.5 Γ Base Γ Height. Measure the longest straight edge (the base) and the perpendicular distance from the base to the opposite corner (the height).
For circular areas, you need the radius (the distance from the exact center to the outer edge). The formula is Ο (3.14159) Γ RadiusΒ². If you only know the diameter (the full width across the circle), simply divide it by 2 to get the radius.
DIYers frequently confuse these three measurements. Here is the breakdown:
A room that is 12 feet wide by 12 feet long is exactly 144 square feet. If you are buying flooring for this room, remember to add 10% for waste, meaning you should purchase enough material to cover 158 square feet.
To calculate drywall square footage, measure the perimeter of the room and multiply it by the ceiling height to get the wall area. Add the ceiling area (Length Γ Width). Finally, subtract the square footage of all doors (approx. 20 sq ft each) and windows (approx. 15 sq ft each). Use our Drywall Calculator to do this instantly.
One acre of land is exactly 43,560 square feet. If you are measuring a large property for fencing or landscaping, our calculator above will automatically convert your square footage into acres.
A standard single-car garage is typically 12 feet by 20 feet, which equals 240 square feet. A standard two-car garage is usually 20 feet by 20 feet (400 square feet) or 24 feet by 24 feet (576 square feet).