About Area Calculator
Area is the size of a flat surface, in square units of the lengths entered. The formulas used are: rectangle a × b, with perimeter 2(a + b); circle π × r², with circumference 2πr; triangle base × height ÷ 2; trapezoid (a + b) ÷ 2 × height; ellipse π × a × b. The ellipse perimeter uses the Ramanujan approximation π(3(a + b) − √((3a + b)(a + 3b))), since no exact simple formula exists.
Also known as: Geometry Calculator.
How to use Area Calculator
- Fill in "Shape", "a", "b" and "c".
- The result appears below and updates as you type.
- Copy the result with the copy button, or download it as a file where that is offered.
Questions about Area Calculator
Which units does the result use?
The same units you enter, squared for area. If you type lengths in metres the area is in square metres and the perimeter in metres. Use one unit for every dimension.
Why is the triangle hypotenuse marked as right-angled only?
The calculator knows only the base and height. Those two define the third side only when they meet at a right angle, where it equals the square root of base² + height².
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