Area Calculator
Pick a shape, enter its measurements and get the area. Perimeters are shown for the shapes where they follow directly from the measurements.
Result
Please correct the highlighted fields.
Area
24
- Perimeter
- 20
How the area of each shape is found
Each shape has its own formula, listed below. For a triangle with three known sides, Heron’s formula finds the area without needing the height; the sides must satisfy the triangle inequality or no triangle exists.
An ellipse has no simple exact perimeter, so the perimeter shown uses Ramanujan’s approximation, which is very accurate for most ellipses. Trapezoids, parallelograms and triangles given by base and height do not show a perimeter because it would need their slanted sides.
Formulas used
Rectangle = length × width
Square = side²
Triangle = base × height ÷ 2
Heron: √(s(s−a)(s−b)(s−c)), s = (a+b+c) ÷ 2
Trapezoid = (a + b) ÷ 2 × height
Parallelogram = base × height
Ellipse = π × a × bWorked example
A rectangle 6 long and 4 wide:
- Area: 6 × 4 = 24
- Perimeter: 2 × (6 + 4) = 20
6 × 4 = 24 square units.
Assumptions and limits
- Shapes are flat and measurements are exact; no rounding is applied before the formula.
- For a circle, use the circle calculator.
- Values up to one billion are accepted.