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Area Calculator

Calculate the area of a rectangle, square, triangle, circle, trapezoid, parallelogram, ellipse or sector. Shows the formula used. Free area calculator.

Area
96 square units
Formula
length × width

Use the same unit for every length; the area comes out in that unit squared.

Area formulas for common shapes

Area is the size of a flat surface, measured in square units. A rectangle is length × width, so 12 × 8 is 96 square units. A triangle is half the base times the height; a circle is π × r²; a trapezoid is the average of its parallel sides times the height. Pick the shape, enter its measurements in any one unit, and the area comes out in that unit squared: square feet, square meters or square inches.

How to use it

  1. 1

    Choose a shape

    Rectangle, square, triangle, circle and more.

  2. 2

    Enter the measurements

    All in the same unit.

  3. 3

    Read the area

    The area and the formula used.

Frequently asked questions

How do I find the area of a rectangle?

Multiply the length by the width.

What is the area of a circle?

π × radius². A circle with a 5 cm radius has an area of 78.54 cm².

How do I find the area of an irregular room?

Split it into rectangles and triangles, work out each area and add them up.

Is anything stored?

No. The calculation runs in your browser.

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