How to Calculate Perimeter and Area Ratio

How to Calculate Perimeter and Area Ratio
••• Kwanchai_Khammuean/iStock/GettyImages

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

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

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

    C=2\pi r

    where r is the radius.

    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.

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

Rectangle

    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.

    Calculate the perimeter using the formula

    2(b+w)=P

    where b is the base and w is the width.

    Calculate the area using the formula

    A=bw

    where b is the base and w is the width.

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

    Tips

    • 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.

Related Articles

How to Find the Ratio of a Rectangle in Geometry
How to Measure Square Centimeters
How to Find the Area of a Polygon
How to Calculate Volume of a Rectangular Prism
How to Find the Radius of a Cone
How to Calculate Diameter to Square Feet
How to Convert Square Dimensions to Round
How to Find the Volume of a Square Pyramid
How to Calculate Area of a Triangle
How to Calculate Height From Volume
How to Find the Volume of a Semicircle
How to Find the Lateral Area of a Square Pyramid
How to Calculate Width
How to Calculate a Circular Area
How to Find the Area of Squares
How to Calculate Volume of a Circular Cylinder
How to Calculate the Acreage of a Triangle
Characteristics of Aquatic Plants
How to Find the Radius of a Sector
How to Measure Square Centimeters