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 is a bar chart where each bar is split into segments that add up to the category's total. A 100% stacked bar chart rescales every bar to the same height so each segment shows a percentage instead. Use standard stacking when totals matter; use 100% stacking when you only care how the mix of parts compares.
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.
Worked example: the same data both ways
Imagine a shop records sales by channel for three quarters (units sold):
| Quarter | In store | Online | Phone | Total |
|---|---|---|---|---|
| Q1 | 60 | 30 | 10 | 100 |
| Q2 | 60 | 60 | 30 | 150 |
| Q3 | 50 | 100 | 50 | 200 |
In a standard stacked bar chart the bars rise from 100 to 150 to 200, so the growth is the headline, and you can see the online segment thickening. In-store sales look roughly flat because 60, 60 and 50 sit on the baseline, where they are easy to compare.
In a 100% stacked bar chart every bar is the same height. Each value is divided by its bar's total: in-store falls from 60% (60 of 100) to 40% (60 of 150) to 25% (50 of 200), while online climbs from 30% to 40% to 50%. The chart now tells a different story, a shift in channel mix, and says nothing about the business growing. Neither is wrong; they answer different questions. When you need both, show the standard stacked chart and add the percentages as labels.
| Question you are answering | Best choice |
|---|---|
| Which category has the biggest total, and what is it made of? | Stacked bar chart |
| How does the share of each part differ between categories? | 100% stacked bar chart |
| How does composition change over a few time periods? | Stacked or 100% stacked bars |
| How does composition change over many time periods? | Stacked area chart |
| Which individual sub-part is larger, exactly? | Grouped bar chart |
Best chart to compare composition over time
Composition over time means watching how the parts of a whole change from period to period: market share by year, budget by category each month, traffic by source each week. With a few periods (roughly up to a dozen), stacked bars work well, because each period is a separate, clearly labelled bar. Choose the 100% version when the shares are the message and the totals swing so much that they would hide the mix. With many periods, a stacked area chart draws the same layers as continuous bands and is easier on the eye; see line vs area chart for when bands beat lines. A series of separate pie charts is the weakest option, because angles in different circles are very hard to compare.
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.
- Check the variant. If every bar ends at the same height and the axis runs 0 to 100%, it is a 100% stacked chart and you are reading shares, not amounts.
- Read the legend and note the order of the segments from the baseline up.
- Compare totals using the bar tops (standard stacked only).
- Read a segment's value by subtracting the value at its bottom edge from the value at its top edge. A segment running from 40 to 70 is worth 30, not 70.
- Compare one part across bars using labels where the segment floats above the baseline.
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. There is also a dedicated stacked bar chart maker that switches between stacked and grouped layouts. For a side-by-side breakdown of the two layouts, read stacked vs grouped bar chart, and for how stacking fits among the other options, see the complete guide to chart types.
Frequently asked questions
What is a stacked bar chart?
A stacked bar chart is a bar chart in which each bar is divided into coloured segments, one per sub-category, piled on top of each other. The full height of the bar is the total for that category and each segment shows how much one part contributes to it.
What is the difference between a stacked bar chart and a 100% stacked bar chart?
A stacked bar chart plots the real values, so bars have different heights and you can compare totals. A 100% stacked bar chart converts each segment to a percentage of its own bar, so every bar is the same height and you compare shares, but the totals disappear.
Are stacked bar charts each value stacked, or does the total bar make up the total value?
Both. Each value is drawn as its own segment, stacked on top of the previous one, and the top of the bar is the sum of all segments, which is the total for that category. In a 100% stacked bar chart the full bar always represents 100% instead of the raw total.
What is the best chart to compare composition over time?
For a handful of time periods, a stacked bar chart works well when totals matter and a 100% stacked bar chart works well when only the shares matter. For many periods, a stacked area chart shows the same thing more smoothly. Avoid a row of pie charts, which are hard to compare.
Are a composite bar chart and a stacked bar chart the same?
Yes. A composite bar chart, also called a component or segmented bar chart, is another name for a stacked bar chart: each bar represents a total and is divided into parts. A percentage composite bar chart is the same as a 100% stacked bar chart.
When is a grouped bar chart better than a stacked one?
Use a grouped bar chart when comparing the individual sub-parts matters more than the total. Because grouped bars all start from the same baseline, their lengths are easy to compare directly, whereas a stacked chart makes any segment that does not sit at the bottom hard to read.