Area Calculator
Calculate the area of rectangles, triangles, circles, and trapezoids.
This tool is for informational and educational purposes only. It is not a substitute for professional financial, medical, legal, or engineering advice. See Terms of Service.
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This calculator finds the area of four common shapes: rectangles, triangles, circles, and trapezoids. It updates results instantly as you type.
- Select a shape. Use the dropdown menu to choose rectangle, triangle, circle, or trapezoid.
- Enter the dimensions. Each shape requires different measurements. Rectangles need length and width, triangles need base and height, circles need the radius, and trapezoids need both parallel sides plus the height.
- Read the result. The area appears immediately with the formula used. You can copy or share the result using the buttons on the result card.
All inputs accept decimal values. The calculator uses standard geometric formulas: length times width for rectangles, half base times height for triangles, pi times radius squared for circles, and the average of the parallel sides times the height for trapezoids.
About Area Calculations
Area measures the size of a two-dimensional surface. It is expressed in square units, such as square meters, square feet, or square centimeters. Knowing how to calculate area is essential in fields like construction, landscaping, interior design, and engineering. For example, you need area to determine how much paint covers a wall, how much carpet fits a room, or how much material is required for a project. Each shape has its own formula derived from fundamental geometric principles. This calculator handles the four most common shapes encountered in everyday math and practical applications.
Frequently Asked Questions
What is the formula for the area of a circle?
The area of a circle is A = pi times r squared, where r is the radius. For example, a circle with radius 5 has an area of approximately 78.54 square units.
How do I calculate the area of an irregular shape?
Break the irregular shape into simpler shapes like rectangles, triangles, and circles. Calculate the area of each piece separately, then add them together. For curved irregular shapes, you may need calculus or approximation methods.
What is the difference between area and perimeter?
Area measures the surface enclosed by a shape, expressed in square units. Perimeter measures the total length around the outside of a shape, expressed in linear units. For example, a 4x6 rectangle has an area of 24 square units and a perimeter of 20 units.