Pick a shape — rectangle, square, circle, or triangle — enter the dimensions, and see the area instantly with the exact formula used.
Results update as you type. Use the same unit for every dimension; the answer is in square units.
The area of a circle is pi times the radius squared: A = π × r². For example, a circle with a radius of 5 has an area of π × 25 ≈ 78.54.
Multiply the base by the height and divide by two: A = ½ × base × height. For example, a triangle with a base of 6 and a height of 4 has an area of 0.5 × 6 × 4 = 12.
A rectangle's area is length × width. A square is a special rectangle, so its area is side × side, written side². For example, a 4 by 7 rectangle is 28, and a square with a side of 5 is 25.