People use pie charts and bar graphs as two ways of representing data in a visual format. Both formats have strengths and weaknesses with regards to displaying data and information.

### Graphic Difference

Pie charts are circles that are broken into different slices based on the percentage of each category, while bar charts use an x/y axis and columns to represent different data. The bars can be either horizontal or vertical.

### Calculation

Bar charts represent raw data. For example, if one category's total is 40,000, then 40,000 is shown on the graph. Pie charts represent percentages of a whole. For example, if a category total equals 40,000, but 40,000 only accounts for 10 percent of the total, that category will make up 10 percent of the circle.

### Time Frame

A bar graph can show change over time, while a single pie chart cannot, only representing the given percentages at a fixed point in time.

### When to Use Bar Graphs

Bar graphs should be used when showing quantities that are either not necessarily linked or demonstrate change over time. For example, use a bar graph to show either company revenue totals over the past decade or raw sales figures for different departments.

### When to Use Pie Charts

Pie charts should be used when the data shows how different categories relate to the whole at a particular point in time, such as either company expense categories or percentages of city statistics in a particular year.