Visualization types

Bar Chart

Comparative

Also known as: bar graph

A bar chart displays categorical data with rectangular bars whose length or height corresponds to the value of each data point.

Bar charts can be visualized using vertical or horizontal bars. Bar charts are best used to compare a single category of data or several. When comparing more than one category of data, the bars can be grouped together to created a grouped bar chart.

Bar charts use volume to demonstrate differences between each bar. Because of this, bar charts should always start at zero. When bar charts do not start at zero, it risks users misjudging the difference between data values.

Examples

Types of Languages Spoken at Home in New York

Source: 2016 American Community Survey 1-Year Estimates

Guidance

In addition to the guidance provided in this section, relevant guidance can also be found in the Agency Logo, Axes, Colors, Grids, Labels, Legends, Source, Titles, Typography sections.

Requirements

Always

Use independent categories of data.
Label each category of data.
When visualizing data between 0% and 100%, start tick marks at 0%.

Never

Never omit the space between bars – otherwise the bar chart will appear to be a histogram.
Never use three dimensional (3D) graphics as they distort the visual calculation of volume.