What Is a Pareto Chart? Definition, Examples, and How to Build One (2026)
A Pareto chart is a bar chart sorted from largest to smallest, with a cumulative percentage line running across it on a second axis. You read it by following the 80% mark on the right axis to where it meets the line. Then look at the bars to the left. Those are the few causes producing most of the effect.
It is the standard way to answer one question: where should we start? That question comes up in support queues, defect logs, overdue invoices and expense lines.
This guide covers the definition, what the chart is for, how it works, how to build one, and where teams misread it.
What is a Pareto chart?
Formally, the chart combines two things on one plot. Bars show the size of each category. A line shows the running total of those bars as a share of the whole.
The bars must be in descending order. Without that, the cumulative line means nothing. It only reads as "how much have we covered so far" when the biggest contributors come first.
The name comes from the Pareto principle, better known as the 80/20 rule. The chart does not assume the split is exactly 80/20; it shows you what your actual split is.
That is the part most explanations skip. It is a measurement, not a confirmation of a rule.
What a Pareto chart is used for
The core use is prioritisation when you have a long list of categories and limited attention.
Three examples make the shape concrete. Support tickets by reason, where a handful of issues generate most of the volume. Manufacturing defects by cause, which is where the chart originated. Overdue receivables by customer, where a few accounts hold most of the balance.
The common thread is that categories are unequal and effort is finite. If your categories are roughly equal in size, the chart will show a nearly straight line and tell you nothing useful.
That is a legitimate finding. A flat curve means there is no small set of causes to attack, which changes the plan.
There is a second condition people forget. The categories have to be independent, because overlapping causes double-count and inflate the leading bars.
Check the unit as well. Ranking by count answers a different question from ranking by cost, and the two orders often disagree.
How a Pareto chart works
The sorted bars
Each bar is one category, measured in whatever unit matters: count, cost, hours, dollars. Sorting descending is what makes the chart readable.
If one category is "Other," keep it at the far right regardless of size. An "Other" bucket in the middle of the sequence breaks the reading of the line.
The cumulative line
For each bar, the line plots the total of that bar and all bars to its left, divided by the grand total. So the last point is always 100%.
Because it is a percentage on a different scale from the bars, it needs its own axis. That secondary axis is what makes this a combination chart rather than a bar chart with a line drawn on it.
Reading the 80% mark
Follow 80% across from the right axis until it meets the line, then drop down. Everything to the left is your priority set.
Note what the answer actually is. It is a count of categories, not a share of them, and the useful sentence is "these four causes account for 80% of the volume."
The 80% line is a convention, not a threshold with any statistical meaning. Some teams work to 70% and some to 90%, and either is defensible if stated.
What the chart never tells you is which of those causes you can actually fix. Ranking by size and ranking by tractability are separate exercises.
How to build one in Excel
Excel builds this chart natively, so you do not need to construct the cumulative column yourself.
Microsoft's documented path is: "Select Insert > Insert Statistic Chart, and then under Histogram, pick Pareto."
The data layout is simple. Microsoft states that you "typically select a column containing text (categories) and one of numbers." It adds that the chart "groups the same categories and sums the corresponding numbers."
That grouping behaviour is genuinely useful. A raw log with one row per ticket can be charted directly, because repeated categories are aggregated for you.
For the horizontal axis, right-click it and open Format Axis, then Axis Options. Microsoft describes By Category as "the default when both data and text are plotted." In that mode "the text categories are plotted on the horizontal axis and graphed in descending order."
The built-in chart is documented for Excel for Microsoft 365, Excel 2024 and Excel 2021. Excel for iPad and iPhone are listed too, along with the Mac versions.
Pareto chart vs. related charts
| Chart | Answers | Use when |
|---|---|---|
| Pareto chart | Which few categories drive most of the total? | Categories are unequal and you must prioritise |
| Plain bar chart | How do categories compare? | Ranking matters but cumulative share does not |
| Waterfall chart | How did we get from a starting figure to an ending one? | Tracking additions and subtractions to a total |
| Funnel chart | Where do people drop out of a sequence? | Stages are ordered and each follows the last |
| Histogram | How is a single numeric variable distributed? | You have measurements, not named categories |
The distinction that matters most is the last row. A histogram bins numbers; this chart ranks named categories, even though Excel files them under the same menu.
How to build a Pareto chart with Powerdrill Bloom
Step 1: Upload your raw log or export
Upload the ticket log, defect list or invoice export as it is, one row per event. Powerdrill Bloom profiles the columns on arrival, so inconsistent category spellings surface before they split one bar into three.
Step 2: Ask for the ranked breakdown in natural language
Name the category column and the measure, and ask which categories account for most of the total. Then ask for the cumulative share so you can see where 80% lands.
Ask the sanity questions in the same pass. Ask whether any category labels are near-duplicates, and whether the top categories still lead when you measure by cost rather than by count.
Step 3: Export the chart, report, or deck
Take out the chart itself, a table of categories with cumulative share, or a slide naming the priority set.
Common mistakes
Leaving the bars unsorted. The cumulative line is meaningless unless categories run largest to smallest. This is the single most common error.
Reading the secondary axis wrong. If its maximum sits above 100%, the 80% gridline lands in the wrong place and you overcount your priority set. Set the maximum to 100%.
Splitting one category across several labels. "Login issue," "Login" and "log-in" become three bars and each looks small. Clean the labels before charting, which our AI data cleaning page covers.
Counting events when cost is the real measure. Fifty cheap tickets and five expensive ones rank differently by count and by dollars. Chart the unit you actually care about.
Treating 80/20 as a law. Your split might be 60/20 or 95/10. Read the line rather than assuming the ratio.
Using it for ordered stages. A drop-off sequence belongs in a funnel. Sorting ordered stages by size destroys their meaning.
Hiding the long tail entirely. Rolling everything small into "Other" is fine, but keep it visible and at the right, so the reader knows how much was folded away.
Conclusion
A Pareto chart is a sorted bar chart plus a cumulative line, and it exists to tell you which few categories deserve attention first. Excel builds it natively under Insert Statistic Chart.
The two things that decide whether yours is correct are the sort order and the secondary axis maximum. Both are quick to check and both are commonly wrong.
If your categories arrive as a messy export rather than a tidy summary, try Powerdrill Bloom on the raw file. See also our guides to turning a CSV file into a chart and the bar graph maker and AI graph maker pages.
Frequently asked questions
What is a Pareto chart used for?
It identifies which few categories account for most of a total, so you know where to start. Common uses include support tickets by reason, defects by cause and overdue balances by customer.
How do I make a Pareto chart in Excel?
Select your category and value columns, then choose Insert, Insert Statistic Chart, and pick Pareto under Histogram. Excel groups repeated categories, sums their values and adds the cumulative line for you.
Why must the bars be sorted descending?
The cumulative line reads as "how much of the total have we covered so far," which only makes sense when the largest contributors come first. Unsorted bars make the line arbitrary.
Is a Pareto chart the same as the 80/20 rule?
No. It is named after the Pareto principle but it measures your actual distribution, which may be nowhere near 80/20. A near-straight line means no small set of causes dominates.
What is the difference between a Pareto chart and a histogram?
A histogram bins a numeric variable to show its distribution. The other ranks named categories and adds a cumulative share, even though Excel groups both under the same chart menu.