How to calculate square footage
Area is length times width. Measure both sides in the same unit, multiply, and you have the area in that unit squared:
Square feet = length (ft) × width (ft)
Measure wall to wall at floor level, and round up to the next inch rather than down. If you measure in feet and inches, convert the inches to a fraction of a foot (6 in is 0.5 ft) or simply type 12’ 6” into the calculator.
Formulas for other shapes
| Shape | Area |
|---|---|
| Rectangle or square | length × width |
| Triangle | base × height ÷ 2 |
| Circle | 3.1416 × radius² (radius = diameter ÷ 2) |
| Ring, such as a path around a tree | 3.1416 × (outer radius² − inner radius²) |
For any other shape, break it into these pieces. An L-shaped room is two rectangles. A room with an angled wall is a rectangle plus a triangle. A bay window is a rectangle plus two triangles.
Converting square feet
| From square feet to | Multiply by |
|---|---|
| Square yards | 0.1111 (divide by 9) |
| Square meters | 0.0929 (divide by 10.764) |
| Acres | divide by 43,560 |
One square meter is 10.764 square feet, and one hectare (10,000 m²) is about 2.47 acres. For land and lots, the square feet to acres calculator converts between all of these.
Using it for materials
Square footage is the starting point for most material estimates. Flooring and tile are sold by the square foot; paint coverage is quoted in square feet per gallon; and mulch, gravel and topsoil only need a depth to turn the area into a volume. For those, use the flooring calculator, tile calculator, paint calculator or cubic yard calculator, which start from the same measurements.