Area calculator
Area and perimeter of rectangles, triangles, circles and trapezoids.
Area
ft²
A 8 by 5 rectangle has an area of 40 ft².
How this is calculated →- Perimeter26 ft
- Formulabase × height
Area formulas
Rectangle (and square): base × height. Triangle: base × height ÷ 2, with the height perpendicular to the base. Circle: π × r². Trapezoid: (long base + short base) × height ÷ 2.
The area comes out in the chosen unit squared: measurements in feet give square feet. To convert, use the area converter.
Frequently asked questions
How do I find the area of a room?
Multiply length by width: 12 ft × 15 ft = 180 sq ft.
What about a square?
Use the rectangle with equal base and height: side × side.
Which value of π is used?
The double-precision value, 3.141592653589793.
How do I find the area of an irregular shape?
Split it into rectangles and triangles, find the area of each part and add them up. An L-shaped room, for example, is two rectangles.
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