How Do You Measure the Area of a Circle?

Measure the area of a circle with a simple formula.

Calculating the area of a circle is one of those formulas that most people learn as a child and then forget if they do not use the formula often. Fortunately, the formula for finding the area of a circle is simple and once you reacquaint yourself with it, your childhood math lessons will likely come back to you quickly. Measure the area of a circle with simple measuring tools, the proper formula and a calculator.

Things You'll Need

• Tape measure
• Paper
• Pencil
• Calculator

Instructions

1. Measure the diameter of the circle with the tape measure. The diameter is a straight line across the center of the circle from one outer edge to the opposite outer edge. Write this measurement down.

2. Divide the diameter by two to find the radius of the circle. The radius is half of the diameter or the distance from the center of the circle to any outer edge. Write this measurement down.

3. Square the radius dimension (multiply it by itself) and then multiply the answer by 3.14 (pi). For example, if the diameter of a circle is 50 feet, divide this by 2 to determine the radius is 25 feet. Square the radius by multiplying it by itself (625 feet) and multiply 625 by 3.14 to get an area of 1,962.5 square feet for the circle.

References

• Clemson Cooperative Extension: Measuring the Area of a Home Lawn
• Course Web: Measurement Formulas