How to Figure Percentage of a Circle Graph

A protractor helps measure angles.
••• Ableimages/Photodisc/Getty Images

A circle graph, also known as a pie chart, shows the makeup of a group of data based on the percentage of the total that each subgroup represents. For example, a circle graph might show the revenue from the four lines of business a company has in place or the amount of sales resulting from each store. Each slice of the circle graph represents a percentage. To find the percentage represented by each slice, you need to know the angle measure of the slice.

    Measure the angle of the sector of the circle graph with a protractor. Line the straight edge of the protractor up with one of the radii that form the sector and then find the angle measure from where the other radius intersects the curved edge of the protractor.

    Divide the angle measure by 360 because to find the portion of the circle represented by the sector. For example, if the sector measures 162 degrees, divide 162 by 360 to get 0.45.

    Multiply the portion by 100 to convert to a percentage. In this example, multiply 0.45 by 100 to find that a sector measuring 162 degrees equals 45 percent of the circle graph.

    Things You'll Need

    • Protractor
    • Calculator

Related Articles

Montessori-Inspired Toys & Kits for Your Little Scientist
How to Calculate Arc Area
How do I Calculate 0.1%?
How to Find the Radius of a Partial Circle
How to Calculate the Diameter of a Circle From a Linear...
How to Solve a Hexagon
How to Figure the Cubic Yards in a Circle
How to Calculate the Diameter of a Rectangle
How to Calculate the Perimeter of Combined Shapes and...
How to Calculate a Circular Area
How to Calculate Roundness
How to Find the Distance Between Two Points on a Circle
How to Figure Out the Slope of a Line
How to Find the Area of a 12-Sided Polygon
How to Calculate the Arc Length, Central Angle, and...
How to Convert Radian to Minutes
How to Find a Percent of a Fraction
How to Calculate Perimeter and Area Ratio
How to Find the Area of a Shaded Part of a Square With...
How to Calculate the Surface Area of a Circle
How to Find a Z Score