Area Calculator
Calculate area of circles, triangles, rectangles, squares, parallelograms, trapezoids, and ellipses. Interactive tool with comparison charts and perimeter.
About This Calculator
Our area calculator supports seven different shapes: circles, triangles, rectangles, squares, parallelograms, trapezoids, and ellipses. Simply select a shape from the dropdown menu and enter the required dimensions — the calculator instantly computes the area using standard geometric formulas. Whether you are a student studying geometry, a DIY enthusiast planning a project, or a professional needing quick measurements, this tool provides accurate results every time.
Each shape uses its specific formula: circle area uses A = πr², triangle uses A = ½ × base × height, rectangle uses A = length × width, square uses A = side², parallelogram uses A = base × height, trapezoid uses A = ½ × (a + b) × h, and ellipse uses A = π × a × b. Results are displayed alongside a comparison bar chart showing both area and perimeter for easy visualization and comparison across shapes.
How to Use
Using the area calculator is straightforward. Start by selecting the shape you want to calculate from the dropdown list. Based on your selection, the relevant input fields appear automatically. Enter the required dimensions in the input fields — for example, radius for a circle, or length and width for a rectangle. Click the Calculate Area button to see the result instantly. Your inputs are saved in the URL, allowing you to bookmark or share the calculation with others.
Frequently Asked Questions
How do you calculate the area of a circle?
Area of a circle is calculated using the formula A = πr², where r is the radius of the circle. Multiply pi (approximately 3.14159) by the square of the radius. For example, a circle with radius 10 has an area of about 314.16 square units.
What is the formula for area of a triangle?
Area of a triangle is calculated as A = ½ × base × height. You can also use Heron's formula when all three sides are known: A = √(s(s-a)(s-b)(s-c)) where s is the semi-perimeter. For a right triangle, the base and height are the two sides forming the right angle.
How do you find the area of a rectangle?
Area of a rectangle is calculated as A = length × width. Simply multiply the length by the width. For example, a rectangle with length 12 and width 8 has an area of 96 square units.
What is the area of a parallelogram formula?
Area of a parallelogram is calculated as A = base × height. Unlike a rectangle, the height is measured perpendicular to the base, not along the sloping side. Multiply the base length by the perpendicular height to get the area.
How do you calculate the area of a trapezoid?
Area of a trapezoid is calculated as A = ½ × (a + b) × h, where a and b are the lengths of the two parallel sides (top and bottom) and h is the perpendicular height between them. Add the parallel sides, multiply by the height, then divide by 2.
What is the formula for area of an ellipse?
Area of an ellipse is calculated as A = π × a × b, where a is the length of the semi-major axis and b is the length of the semi-minor axis. Multiply pi (approximately 3.14159) by the product of both axes.
What is the difference between area and perimeter?
Area measures the space inside a shape, expressed in square units. Perimeter measures the total distance around the boundary of a shape, expressed in linear units. For a rectangle, area = length × width while perimeter = 2 × (length + width). Our calculator shows both measurements for comparison.
How do you find the area of a square if you only know the side length?
Area of a square is calculated as A = side², where the side is the length of one edge. Simply square the side length. For example, a square with side 12 has an area of 144 square units. All four sides are equal, so only one measurement is needed.