Pareto Principle
Also known as 80/20 Rule
For many outcomes, roughly 80% of the effects come from about 20% of the causes — so a few features, users or issues usually matter most.
See it in action
The same screen without and with Pareto Principle. Watch both sides play out, then compare the outcome.
Spreading effort evenly leaves the few features that matter most under-invested.
Measure first: when a vital few features drive most of the value, that's where effort pays off.
What to watch: the steep drop after the first two bars — the vital few versus the useful many.
Use data to find the vital few (features, bugs, screens) and prioritise them.
Treat 80/20 as an exact law, or delete the long tail without checking who depends on it.
Key takeaways
- Find the small set of journeys that drive most value and perfect them first.
- Prioritize fixes by impact, not by count.
- The 80/20 split is an approximation, not a law of nature — check your own data.
Quick facts
- Also known as
- 80/20 Rule
- Described by
- Vilfredo Pareto (generalised by Joseph Juran)
- Year
- 1896
- Category
- Product strategy
- Related laws
- Occam's Razor, Parkinson's Law, Cognitive Bias, Kano Model
Pareto Principle explained
The Pareto Principle, or 80/20 rule, observes that roughly 80 percent of effects come from 20 percent of causes. The exact numbers vary, but outcomes are rarely distributed evenly.
In products, a small number of features usually account for most usage, a small number of bugs cause most crashes, and a small set of customers often generate most revenue or support tickets.
Applying the principle means identifying that vital few and focusing design and engineering effort where it will have the biggest impact.
Where it comes from
Named after Italian economist Vilfredo Pareto, who observed in the 1890s that about 80% of land in Italy was owned by about 20% of the population. Quality-management pioneer Joseph Juran generalized it as the 'vital few and trivial many' in the 1940s and named it after Pareto.
How it shows up in apps
A small number of flows — usually onboarding, the core action and checkout — account for most retention and revenue. Concentrating research and fixes there produces outsized results.
Pareto Principle examples
Analysis shows that most support tickets come from two screens. Redesigning just those two cuts ticket volume dramatically.
Feature usage
Analytics often show that a handful of features account for most daily usage. Polishing those features improves the experience for most users more than adding new ones.
Bug fixing
Software teams frequently find that a small share of reported bugs causes the majority of crashes or errors, so fixing those first delivers the most stability.
Onboarding focus
Instead of introducing every feature, onboarding that focuses on the few actions most linked to retention gets more users to value faster.
How to apply Pareto Principle
- Use analytics to identify the features and flows that drive most usage and value.
- Prioritise improvements to the vital few before expanding scope.
- Make the most-used actions the most prominent in the interface.
- Use the principle to guide research: focus on the user segments and journeys with the biggest impact.
- Revisit regularly; the vital few change as the product and audience evolve.
Want Pareto Principle checked in your own product? Our saas ux audit evaluates it alongside the other principles that shape how users decide, onboard and stay.
Common mistakes
- Treating 80/20 as an exact ratio rather than a rule of thumb.
- Removing features used by a small but critical group, such as administrators or accessibility users.
- Focusing only on the majority and ignoring high-value minority segments.
How to measure it
Rank features, pages or issues by their contribution to key outcomes (usage, revenue, errors) and plot the cumulative share. If a small share drives most of the outcome, prioritise those items and measure improvements against them.
Frequently asked questions
What is Pareto Principle?
For many outcomes, roughly 80% of the effects come from about 20% of the causes — so a few features, users or issues usually matter most.
Where does Pareto Principle come from?
Named after Italian economist Vilfredo Pareto, who observed in the 1890s that about 80% of land in Italy was owned by about 20% of the population. Quality-management pioneer Joseph Juran generalized it as the 'vital few and trivial many' in the 1940s and named it after Pareto.
How does Pareto Principle apply to app design?
A small number of flows — usually onboarding, the core action and checkout — account for most retention and revenue. Concentrating research and fixes there produces outsized results.
Who discovered the Pareto Principle?
Economist Vilfredo Pareto observed in the 1890s that about 80 percent of land in Italy was owned by about 20 percent of the population. Management consultant Joseph Juran later generalised it.
How is the Pareto Principle used in UX?
Teams use it to focus on the small set of features, flows and issues that have the largest impact on users and business outcomes.
How do you measure Pareto Principle in a product?
Rank features, pages or issues by their contribution to key outcomes (usage, revenue, errors) and plot the cumulative share. If a small share drives most of the outcome, prioritise those items and measure improvements against them.
Sources
- Pareto, V. (1896). Cours d'économie politique. Lausanne. Find on Google Scholar ↗
- Juran, J. M. (1951). Quality Control Handbook. McGraw-Hill. Find on Google Scholar ↗
Related laws
Product strategyOccam's Razor
Among solutions that work equally well, prefer the one with the fewest assumptions and parts — in design, the simplest option that does the job.
Product strategyParkinson's Law
Work expands to fill the time available for its completion — and users' tasks expand to fill the time an interface allows.
Decision-makingCognitive Bias
A cognitive bias is a systematic error in thinking — a mental shortcut that predictably skews how people perceive information and make decisions.
Product strategyKano Model
Features affect satisfaction in different ways: basic needs prevent dissatisfaction, performance features increase satisfaction proportionally and delighters create unexpected joy.
Pareto Principle in practice
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Certifications that test it
- Free certification · UX/UI, Design, Research & CreativeUX Design CertificationCertifies that you can take a product problem from user need to a tested, usable flow — research, information architecture, interaction design and usability evaluation.
- Free certification · UX/UI, Design, Research & CreativeProduct Design CertificationCertifies end-to-end product design: framing problems against business goals, designing and shipping solutions with engineering, and measuring their impact.
- Free certification · UX/UI, Design, Research & CreativeUX Research CertificationCertifies that you can plan, run and synthesize user research that changes decisions — method choice, recruiting, interviewing, usability testing, surveys and analysis.
- Free certification · UX/UI, Design, Research & CreativeDesign Systems CertificationCertifies that you can build, document, govern and scale a design system — tokens, components, documentation, adoption and design–engineering collaboration.
- Free certification · Digital Marketing, SEO, AEO & GrowthConversion Rate Optimization (CRO) CertificationCertifies that you can find and fix conversion leaks with evidence — funnel analysis, research, hypothesis design, A/B testing and landing-page and checkout UX.
- Free certification · Product, Project Management & Business AnalysisProduct Manager CertificationCertifies that you can run product well — discovery, strategy and prioritization, metrics, delivery with design and engineering, and launch.
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