# How To Calculate Perimeter And Area Ratio

The perimeter of a shape is the measure of the length of a shape around its outermost extremities. The area of a shape is the amount of two-dimensional space that it covers. The ratio of the perimeter to the area of a shape is simply the perimeter divided by the area. This is easily calculated.

## Circle

### Step 1

Find the radius of your circle. This is the distance from the center to the outer edge.

### Step 2

Calculate the perimeter or circumference of the circle. This can be done using the equation

\(C=2\pi r\)

where *r* is the radius.

### Step 3

Calculate the area of the circle. This can be done using the equation

\(\text{Area}=\pi r^2\)

where *r* is the radius of the circle.

### Step 4

Divide the perimeter by the area to obtain the ration of perimeter to area.

## Rectangle

### Step 1

Find the length and width of the rectangle. This will be the measurement of one of the long sides and one of the short sides.

### Step 2

Calculate the perimeter using the formula

\(2(b+w)=P\)

where *b* is the base and *w* is the width.

### Step 3

Calculate the area using the formula

\(A=bw\)

where *b* is the base and *w* is the width.

### Step 4

Divide the perimeter by the area to obtain the ration of the perimeter to the area.

### TL;DR (Too Long; Didn't Read)

There are an infinite variety of shapes. If you don't know the formulas for a shape, get creative and try breaking it down into smaller rectangles.

### References

### Cite This Article

#### MLA

Infiesto, Josh. "How To Calculate Perimeter And Area Ratio" *sciencing.com*, https://www.sciencing.com/calculate-perimeter-area-ratio-8144194/. 26 October 2020.

#### APA

Infiesto, Josh. (2020, October 26). How To Calculate Perimeter And Area Ratio. *sciencing.com*. Retrieved from https://www.sciencing.com/calculate-perimeter-area-ratio-8144194/

#### Chicago

Infiesto, Josh. How To Calculate Perimeter And Area Ratio last modified August 30, 2022. https://www.sciencing.com/calculate-perimeter-area-ratio-8144194/