Pie graphs illustrate the component parts or percentages of a whole, where the values must add up to 100%. Pie charts are the least efficient means of charting small data sets and are not often used in the sciences, but are common in business and general information graphics.

Stacked bars are often used as space-efficient replacements for multiple pie charts. Neither pie graphs and stacked bar charts are impressive if too many elements are displayed. About six segments would be the limit before visual confusion sets in.

Poor Example

Good Example

• Use a maximum number of six slices in a pie chart. If you need more, group smaller ones into one group titled “miscellaneous” or “other.” Pull this group out into another chart.

• Order slices beginning with the largest slice or the most important data starting at the 12 o’clock position and arrange subsequent slices clockwise. The most important slice is in the upper-right quadrant. Arrange slices in order from largest to smallest.

• Emphasize one slice by “exploding it” or moving it out of the circle. You can also choose a color or fill pattern different from the rest of the slices to emphasize a particular slice.

• For stacked bar charts, labels are placed to the right of the vertical graph or above a horizontal graph.

• For pie charts, labels are placed inside the segments if the labels are brief and segments are large enough. Otherwise, labels are listed next to the segment.

• Percentages should be included in labels. Use whole numbers.

• Percentages are usually separated from the labels (on separate line) and are smaller in size than the labels.

• Labels and percentages should be placed horizontally and not at an angle

• Each slice should be easily distinguishable from the rest and clearly labeled.