Area Calculator
Calculate area of circles, triangles, rectangles, squares, parallelograms, trapezoids, and ellipses. Free interactive geometry tool.
About This Calculator
Our area calculator supports seven different geometric shapes: circles, triangles, rectangles, squares, parallelograms, trapezoids, and ellipses. Simply select a shape from the dropdown and enter the required dimensions to instantly compute the area and perimeter.
Area Formulas
Circle: A = pir^2 -- The area is pi multiplied by the square of the radius. The radius is the distance from the center to any point on the circle.
Triangle: A = 1/2 x base x height -- The area is half the product of the base length and the perpendicular height from the base to the opposite vertex.
Rectangle: A = length x width -- Multiply the length by the width. The perimeter is 2 x (length + width).
Square: A = side^2 -- Since all four sides are equal, square the side length. The perimeter is 4 x side.
Parallelogram: A = base x height -- The area is the product of the base and the perpendicular height (not the slant height).
Trapezoid: A = 1/2 x (a + b) x h -- The area is half the sum of the two parallel sides multiplied by the perpendicular height between them.
Ellipse: A = pi x a x b -- The area is pi multiplied by the product of the semi-major axis (a) and semi-minor axis (b).
All results are displayed alongside a bar chart comparing the areas of selected shapes for quick visual reference.
Frequently Asked Questions
How do you calculate the area of a circle?
Area of a circle is calculated using the formula A = pir^2, where r is the radius. Multiply pi (approximately 3.14159) by the square of the radius.
What is the formula for the area of a triangle?
Area of a triangle is A = 1/2 x base x height. When all three sides are known, use Heron's formula: A = sqrt(s(s-a)(s-b)(s-c)) where s is the semi-perimeter.
How do you calculate the area of a rectangle?
Area of a rectangle is A = length x width. Simply multiply the length by the width to get the total area in square units.
What is the formula for the area of a square?
Area of a square is A = side^2. Since all sides are equal, multiply the length of one side by itself.
How do you calculate the area of a parallelogram?
Area of a parallelogram is A = base x height. The height is the perpendicular distance between the base and the opposite side.
What is the formula for the area of a trapezoid?
Area of a trapezoid is A = 1/2 x (a + b) x h, where a and b are the lengths of the parallel sides and h is the perpendicular height between them.
How is the area of an ellipse calculated?
Area of an ellipse is A = pi x a x b, where a is the semi-major axis and b is the semi-minor axis. It is an extension of the circle area formula.