Square footage calculator
Pick a shape, enter the dimensions and get the area instantly in square feet, square meters, square yards, acres and hectares. Works for floors, rooms, walls and lots.
See your design as an AI render — free- m²
- 11.15
- sq yd
- 13.33
- acres
- 0.002755
Area = length × width
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How to calculate square footage
Area is how much surface a shape covers. Every formula uses two measurements in the same unit.
- 1
Measure in one unit
Measure the sides in feet (or meters). If one measurement is in inches, convert it first: 30 in is 2.5 ft.
- 2
Rectangle: length × width
A 12 × 10 ft room is 12 × 10 = 120 sq ft. In metric, 5 × 4 m is 20 m².
- 3
Other shapes
Triangle: base × height ÷ 2, so 6 × 4 ft is 12 sq ft. Circle: π × diameter² ÷ 4, so a 10 ft circle is 78.54 sq ft. Trapezoid: (5 + 3) ÷ 2 × 4 = 16 sq ft.
- 4
Composite shapes: split and add
An L-shaped room becomes two rectangles: 12 × 10 ft plus 6 × 5 ft is 120 + 30 = 150 sq ft. For cut-outs, work out the missing part and subtract it.
Area formulas
The same formulas the calculator uses.
| Shape | Formula | Where you find it |
|---|---|---|
| Rectangle or square | length × width | Floors, rooms, walls, lots |
| Triangle | base × height ÷ 2 | Gables, corners, irregular lots |
| Circle | π × diameter² ÷ 4 | Round patios, planters, columns |
| Trapezoid | (side A + side B) ÷ 2 × height | Irregular lots, roof planes |
Frequently asked questions
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