Stacked Bar Charts
GUIDEHow a stacked bar chart shows totals and composition at once, the two variants, and the trap to avoid.
A stacked bar chart does two jobs in one picture. Like an ordinary bar chart, it lets you compare totals across categories by bar height. But it also splits each bar into coloured segments, so you can see the composition inside every total at the same time. It answers a layered question: how big is each category, and what is each one made of?
How a stacked bar chart works
Each bar represents one category — a time period, a group, a region. Within that bar, the value of each sub-part is drawn as a segment, and the segments are piled on top of one another. The first segment sits on the baseline, the next starts where the first ended, and so on. The result is that the top of the whole bar marks the total, while the height of each coloured band shows that part's contribution.
The same segment colour means the same sub-category across every bar, so a legend lets the reader trace one part from bar to bar. This is the chart's strength: it shows the big picture (which totals are largest) and the breakdown (what is inside each total) without forcing the reader to look at two separate charts.
Stacked vs. 100% stacked
There are two flavours, and choosing between them depends on whether the totals or the shares are your message.
- Standard stacked. Bars keep their real values, so they differ in height. You can compare totals between categories and see the parts. Use it when the size of the whole still matters.
- 100% stacked. Every bar is stretched to the same full height, and each segment shows its percentage of that bar. You give up the totals entirely in exchange for a clean comparison of composition. Use it when only the mix matters — for instance, comparing how the same shares shift between categories.
If the reader needs to know "which total is bigger?", keep a standard stacked chart. If they only need "how does the mix differ?" and the totals are a distraction, switch to 100% stacked.
When a stacked bar beats a grouped bar
The usual alternative is a grouped (clustered) bar chart, which places the sub-parts side by side instead of piling them up. Each has a sweet spot:
- Reach for stacked when the total is the headline and the breakdown is supporting detail, or when you have many sub-parts that would make a grouped chart a forest of thin bars. Stacking keeps the totals front and centre and stays compact.
- Reach for grouped when comparing the individual sub-parts is the point. Because grouped bars share a baseline, their lengths line up and the eye compares them accurately — something a stacked chart cannot offer for any segment that floats above the baseline.
Both relate to the pie chart as well: a single stacked bar is essentially a pie's composition stretched straight, and unlike a pie it lets you place several totals next to one another for comparison.
The mistake that matters most: floating middle segments
Only the bottom segment and the total sit on a fixed baseline, so only they are easy to compare across bars. Every segment in the middle starts at a different height in each bar, which means the eye cannot reliably judge whether it grew or shrank — this is the classic stacked-bar trap. If a middle part is the one you most need to compare, put it on the baseline, switch to a grouped bar chart, or pull it onto its own chart. Other pitfalls: too many segments turning each bar into confetti, and colour schemes where neighbouring segments are hard to tell apart.
How to read a stacked bar chart
Read it in two passes. First, compare the full heights to see which totals are largest. Then pick one segment colour and follow it across the bars, reading its band thickness — but remember that bands above the baseline are hard to measure precisely, so lean on labels for the middle parts. The bottom segment and the total are the two quantities you can trust your eye to compare directly.
Make a stacked bar chart
Build one in the bar chart maker — enter a value for each segment within every category, choose stacked or 100% stacked, recolour the segments, and export a PNG or SVG, free and without signup. For how stacking fits among the other options, see the complete guide to chart types.