Bar charts and bar graphs: the full family explained.

What is a bar graph?

A bar graph, also called a bar chart, uses one bar per category, with the bar's length or height standing in for its value. The format works because comparing lengths is one of the easiest visual tasks for a human eye, which is why bar graphs remain the default choice for straightforward comparisons across almost every business function.

Vertical bars are sometimes called a column chart, and horizontal bars keep the name bar chart. Beyond that basic split, the family branches into seven types depending on what you need to show alongside the comparison itself.

The seven bar chart types

Each type in the family answers a slightly different question. Knowing which question you are asking is usually enough to pick the right one.

• Clustered bar chart, one bar per series placed side by side within each category. Use it when the comparison between series matters more than any total.
• Stacked bar chart, series layered into a single bar per category. Use it when the total and its composition both matter.
• 100% stacked bar chart, every bar normalized to the same height so only the mix is compared, not the size.
• Combo chart, bars paired with a line, usually on a secondary axis, for two measures with different units.
• Waterfall chart, floating bars bridging a starting value to an ending value through a series of gains and losses.
• Bar mekko chart, bar width varies by a second measure alongside the usual bar height.
• Marimekko chart, both column width and segment height carry meaning, for two dimensions of share at once.

Choosing between them

Start by asking what question the chart needs to answer, then let that question point you to the type.

• Comparing categories with no interest in a combined total: clustered bar.
• Showing a total made up of parts: stacked bar.
• Comparing mix while ignoring size differences: 100% stacked bar.
• Explaining what changed between two numbers: waterfall.
• Pairing two measures on different scales: combo.
• Adding a second measure through bar width: bar mekko or, with composition too, marimekko.

Horizontal vs vertical bars

Vertical bars, sometimes called columns, are the default across most of this family. Switch to horizontal bars when category labels are long and need room to sit flush against each bar, or when you are presenting a ranked list, since a horizontal layout naturally reads top to bottom like a leaderboard.

Bar graph vs histogram

A bar graph compares discrete, unrelated categories such as product lines or regions. A histogram groups continuous data into equal-width bins, such as ages zero to ten, ten to twenty, and so on, and shows how many observations fall into each bin. Histograms have no gaps between bars because the bins are contiguous ranges, while a bar graph's gaps signal that the categories are independent of each other.

Best practices across the family

• Start every value axis at zero. A truncated axis exaggerates differences and undermines credibility in front of an audience that checks the numbers.
• Order bars with intent. Sort largest to smallest for a ranking, or keep chronological order for time-based categories.
• Use color to encode a variable, not to decorate. A rainbow of unrelated colors across bars adds noise, not information.
• Add data labels when the chart will be viewed without narration, in a printed deck or a shared file.
• Pick the narrowest type that answers the question. A stacked bar chart used to make a simple comparison usually just adds friction.