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Area Calculator Guide
Find the area of a rectangle, square, circle, triangle, trapezoid, or parallelogram. Pick a shape, enter its dimensions, and the area (and perimeter where it applies) is calculated instantly.
Rectangle: length × width · Circle: πr² · Triangle: ½ × base × height · Trapezoid: ½(a + b) × height · Parallelogram: base × height.
How Do I Calculate Area?
Each shape has its own formula. For a rectangle, multiply length by width; for a circle, multiply pi by the radius squared. For example, a circle with radius 5 has an area of about 78.54 square units.
Area vs Perimeter
Area measures the space inside a shape (in square units), while perimeter measures the distance around it. A circle's perimeter is called its circumference, equal to 2πr.
Related: Square Footage, Circle Calculator, and Volume Calculator.
Frequently Asked Questions
How do I calculate the area of a shape?
Use the formula for that shape — for example, length times width for a rectangle, or pi times radius squared for a circle.
What is the area of a circle?
It is pi multiplied by the radius squared (πr²); a radius of 5 gives about 78.54 square units.
What is the difference between area and perimeter?
Area is the space inside a shape in square units, while perimeter is the total length of its boundary.
What units does this use?
The area is in square units of whatever unit you enter — square feet if you enter feet, square meters if you enter meters.
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