# How to Do Proportional Circles

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A circle is a geometric shape that is perfectly round; every point along its edge is the same distance from the centre. Because of this characteristic, all true circles are proportional to each other.

In fact, the proportion of every circle's circumference (length around its edge) to its diameter (length across its centre) is the same number: pi (approximately 3.14). Proportional circles are often used in making maps and charts to show different values -- the size of the circle communicates the total amount. All you need to draw proportional circles is a tool called a compass.

• A circle is a geometric shape that is perfectly round; every point along its edge is the same distance from the centre.

Decide the size of your first circle's radius. This is the length from the centre to the edge.

Using a ruler, draw a straight line on a piece of paper that is the length of the radius.

Fasten a pencil into a compass.

Place the pointed end of the compass at one end of your radius . This will be the centre of the circle.

• Using a ruler, draw a straight line on a piece of paper that is the length of the radius.
• Place the pointed end of the compass at one end of your radius .

Place the tip of the pencil at the other end of the radius line, and pivot it all the way around the centre. This is your first circle.

Repeat steps one through five with a different length for the radius. You now have two proportional circles on the page.