Pareto Principle

Synonyms: 80/20 rule, the Law of the Vital Few

Pareto Principle states that 80% of consequences come from 20% of causes. Speaking of UX, this principle goes like this: 80% of users use 20% of your features or 20% of the code causes 80% of the errors. In simple terms, this principle means that a small amount of effort has a significant impact.


Pareto Principle visualization by Jose Mendoza


Wilfredo Pareto, an Italian economist, noted that 80% of Italy's land belongs to 20% of the population. He then carried out surveys on a variety of the other countries and found that a similar distribution applied. Despite its origins, this principle can be applied to everyday life, economics, and design.

Tips & Tricks

  1. Pareto Principle helps you to make better decisions in your work whether you're building a website or software.
  2. Put the main effort into the tasks that will bring the greatest benefit to your users.
  3. Use this principle to prioritize development and address design issues that are important to the user experience.
  4. Be aware of sample sizes and other forms of data that can redefine the Pareto Principle in fact.


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