Find the vital few causes that drive most of the pain.
Pareto analysis is the data-driven end of root cause work. If 5 Whys drills depth and Fishbone maps breadth, Pareto tells you which branch to drill. Before you run another RCA session on a vague hunch, plot your defects, your complaints, or your downtime against the 80/20 curve and see which categories actually matter.
The 80/20 rule was first described by economist Vilfredo Pareto in 1896 (observing that 80% of Italian land was owned by 20% of the population). Joseph Juran later generalised it for quality management: in most processes, roughly 80% of the problems come from roughly 20% of the causes.
That ratio isn’t magic — it can be 70/30 or 90/10 depending on the system. What matters is the shape: a few categories dominate, and that’s where you should spend your time. Pareto’s role in RCA is to stop you from running a 5 Whys on a cause that contributes 2% of the pain.
Not sure where to start? The Excel tutorial is the fastest path if you already have data in a spreadsheet. The complete guide is better if you’re new to the method.
Five articles on Pareto analysis
The complete guide for theory, six worked examples, a step-by-step Excel tutorial, and a free template.
Pareto Analysis: The Complete Guide to the 80/20 Rule
Origin with Vilfredo Pareto, the 80/20 rule in RCA, how to build a Pareto chart, and when the distribution doesn't fit 80/20.
ExamplesPareto Chart Examples: 6 Real Case Studies
Defect analysis, customer complaints, downtime causes, inventory ABC, bug triage, and marketing spend — full Pareto workflows.
Excel TutorialHow to Create a Pareto Chart in Excel: Step-by-Step (2026)
Nine-step tutorial for Excel 2016+: data prep, sorting, cumulative %, combo chart with secondary axis, and the 80% cut-off line.
TemplateFree Pareto Chart Template — Excel & Google Sheets
Blank Pareto worksheet with auto-sorting, cumulative percentage formula, chart preset, and worked sample data.
FacilitationHow to Facilitate a Pareto Workshop: Data Prep, the 80/20 Boundary & Hand-off to Deeper RCA
The shortest workshop in RCA — 60-90 min of interpretation, not analysis. Data-readiness, category definition, the 80/20 boundary debate, hand-off to 5 Whys/Fishbone, and 8 Pareto-specific pitfalls.
Before you plot your first Pareto
Does the distribution always have to be 80/20?
No. 80/20 is a rule of thumb, not a law. Real systems show 70/30, 90/10, even 50/50 in rare cases. The value of a Pareto chart is the shape: a steep drop-off means a few causes dominate; a flat chart means every cause is roughly equal and Pareto isn’t the right tool — try Fishbone or FMEA.
What’s the cumulative percentage line for?
It lets you visually identify the 80% cut-off — the bars under the point where the cumulative line hits 80% are your “vital few.” Without it, you’re just eyeballing the bar chart. The Excel tutorial shows how to build it as a secondary-axis line on a combo chart.
When should I pick Pareto over 5 Whys?
Pick Pareto first when you have data about multiple failure categories and need to decide where to invest. Pick 5 Whys after Pareto has told you the category. Running 5 Whys on a gut-feel category is the most common RCA mistake. See the full comparison.
Can Pareto work on non-manufacturing data?
Yes. Customer complaints by root cause, support tickets by product area, marketing spend by channel, bug reports by module — anything you can categorise and count. The examples article includes six domains beyond manufacturing.
Is there an online Pareto chart maker?
Yes — the free Pareto tool takes pasted data and renders a chart in the browser, with cumulative % line and 80% cut-off automatically. For a downloadable starting point, grab the free template.
Build a Pareto chart in your browser
Paste your data, pick your categories, get an instant chart with cumulative % line. No Excel gymnastics, no signup.