How to Make a Pie Chart

21 de enero de 2013

How to Make a Pie Chart

Pie charts, a form of an area chart, are an easy way to visualize percentage breakdowns of a total. They're useful for analyzing polls, statistics, and managing money and data. And they make an excellent visual display for explaining data to other people, whether you're doing a school project, a work presentation or pitching sales figures to clients.

Edit Steps

Organize your information. Gather your numerical data (or information) and write it down in a single place.

Add the data all together and reach a sum. When you're figuring out degrees later, this number will be your denominator.

Know the angle between the two sides of the piece. To do so, multiply your percentage (still in decimal form) by 360.
- The logic behind this is that there are 360 degrees total in a circle. If you know that 14,400 is 30 percent of the whole (or 0.30), then you're just trying to figure out what 30% of 360 is.
- Add up all the degrees you calculate from this step. They should equal 360. If they don't, you've missed something.

Use a mathematical compass to draw a circle. To draw a pie chart accurately, you need to get a perfect circle. This can be done using a compass (and a protractor to measure the angles). If you don't have a compass, try tracing around a circle template, using something round such as a lid or a CD.

Draw the radius. Start in the exact center of the circle and draw a straight line to the outside of the circle. (Hint: make a dot with the compass to find the center.)
- The straight line can be vertical (12 or 6 o'clock on the clock face) or horizontal (9 or 3 o'clock on the clock face). The segments you create then follow either a clockwise or counter-clockwise sequence.

Place your protractor on the circle. Position it on the circle so that the 90 degrees crosshair is situated directly above the center of the circle. The zero point should be vertically aligned along the vertical plot line.

Draw each section division. Draw the sections by marking the first division against the edge of the protractor at the correct angle, using the angle formulations you got in the earlier step. Each time you add a section, the radius changes to the line you just drew; rotate your protractor accordingly.
- When marking the angle lines, make sure they are sharp and fine, to keep them clear to read.

Color each segment. You can use color, patterns or just words, depending on what meets your purpose best. Add the name of the sections and the percent they represent to the chart.
- Color each section of the pie chart a different color/pattern to easily visualize the results.
- If you drew everything in pencil first, always ink in the circle before coloring in any of the segments. This is because the circle is the most trickiest part to draw accurately.
- Labels or words added to segments should stay horizontal and centered (the same visual distance from the edge for each segment). This makes them easier to read.

Edit Tips

If you do not have a very good compass, it is easier to draw the circle by holding the compass still and turning the paper.

Remember that all good graphs have a title and labels.

More sophisticated versions of the pie chart include highlighting a segment by removing it, or making an "exploded pie", where each segment is pulled apart. These can be done manually or using a computer program.

As you gain confidence, you can shift the perspective of the pie chart around, including setting it on its side, turning it 3D or stacking various pies. These are more advanced versions and require more detailed work and knowledge.