# Area by Diameter

To get a circle’s area by diameter, you need to know the diameter first. The following steps will explain how this is done.

### How to Get the Area

Start by getting the diameter of the circle. Get the circle’s circumference and divide this by pi. Next you have to divide the diameter by two to get the radius. If the circle has a 13 inch diameter, divide 13 by 2. The result is 6.3, which is the radius. Next, multiply the radius by itself. This will square the radius.

In this case you should multiply 6.5 by 6.5. The result is 42.25 inches. Multiply this number by 3.14 (pi). This is the area of the circle. By multiplying 42.25 sq in by 3.14, you will get 132.665 square inches. This is the circle’s area.

### More about Circle Circumference and Area

To clarify, the circumference of a circle is the shape’s boundary length. Suppose you shape a wire into a circle. The wire forming the circle boundaries is the circumference. The circumference is also known as the perimeter.

The area is the square units within the circle. Assume you have a piece of paper shaped into a circle. If you want to color it red, the area you paint on is the area.

### Defining Area

Simply put, an area refers to the extent of a shape or 2D surface. It can be seen as a material with a specified thickness. Another way to describe an area is the amount of paint required to conceal a surface. The shape of an area can be determined by comparing its shape to squares of a specific size.

### Calculating Semi Circle Diameters

Get its diameter by multiplying the semi circle’s radius by 2. If the

radius is 5, its diameter is 10. Deduct the circumference off the perimeter. The result is the diameter. If the circumference is 30, its perimeter is sixty.

Deduct the number and the result is 6. The circumference should be multiplied by two. Divide the number by pi. The result is the diameter. If the circumference is 25, multiply it by 2. The result is fifty. Divide this by pi. The result is 15.915. This is the diameter.

There are now calculators that can get area by diameter. They are available on the Internet. These are free and can be used by anyone. Just make sure to input the proper numbers. Otherwise the results will not be valid.