Add up the area of rooms, yards or lots, one shape at a time. Get the total in square feet, square yards, square meters and acres, plus an optional cost.
Quick answers
Square footage of a rectangle = length × width in feet; a 12 × 15 ft room is 180 sq ft.
For L-shaped or irregular spaces, split them into rectangles, circles and triangles and add the areas.
1 square yard = 9 sq ft, 1 square meter = 10.764 sq ft and 1 acre = 43,560 sq ft.
How to use the square footage calculator
Measure the longest straight walls or edges with a tape measure, in feet. Use inches for small spaces if that is easier.
Break odd shapes into rectangles, circles and triangles. An L-shaped room is two rectangles.
Click Add another area for each piece. The calculator adds them up.
Enter a price per square foot to estimate the cost of flooring, sod, paint prep or any material priced by area.
Formulas
Shape
Area formula
Example
Rectangle
length × width
12 × 15 ft = 180 sq ft
Circle
π × (diameter ÷ 2)²
10 ft across = 78.5 sq ft
Triangle
base × height ÷ 2
10 × 8 ft = 40 sq ft
Worked example: an L-shaped living room
Split it into a 12 × 15 ft section (180 sq ft) and an 8 × 6 ft nook (48 sq ft). The total is 228 square feet, or 25.3 square yards. With 10% extra for flooring cuts, buy enough for about 251 square feet.
Unit conversions
1 square yard = 9 square feet
1 square meter = 10.764 square feet
1 acre = 43,560 square feet
Common questions
How do I calculate square footage?
For a rectangle, multiply length by width in feet. A 12 × 15 ft room is 180 square feet. For L-shaped or irregular spaces, split them into rectangles, calculate each one and add them together.
How do I find the square footage of a circle?
Multiply 3.1416 by the radius squared. The radius is half the diameter, so a 10 ft circle is 3.1416 × 5 × 5 = 78.5 square feet.
How many square feet are in a square yard?
Nine. A square yard is 3 ft × 3 ft. Carpet and sod are often priced by the square yard, so divide square feet by 9.
How many square feet are in an acre?
43,560 square feet. A quarter-acre lot is 10,890 square feet.
Should I add extra when buying flooring?
Yes. Flooring is usually bought with 5% to 15% extra for cuts and mistakes, more for diagonal layouts or patterned tile. Check the manufacturer's guidance for your product.