You may have heard someone say that 20% of your clients bring you 80% of all the revenue you'll make. Or that 20% of the people in x country hold 80% of the wealth.

These statements are referencing something called the Pareto Principle, or the 80-20 rule. The principle basically states that a small percentage of causes are responsible for a large percentage of results.

Let's dive in and look at the Pareto Principle and its related concepts in a bit more detail.

What is the Pareto Principle?

In the 1940s, an engineer and management consultant named Joseph Juran came across the work of Italian economist Vilfredo Pareto. Pareto had noticed that around 80% of the land in Italy was owned by only 20% of the population.

Juran observed that this pattern applied to many areas of economics, business, math, and other sciences. He applied the principle to issues of quality control, noting that 80% of problems in business and manufacturing could be attributed to just 20% of the causes.

Juran was the one who named the Pareto Principle and described its parts as "the vital few and the trivial many." This implies that fewer causes/people are important and impactful while many outcomes are affected by those few causes.

Fun fact before we move on: the legend is that Vilfredo Pareto first noticed this distribution in his garden. He saw that around 20% of his pea plants produced about 80% of the fruit. That's what supposedly gave him the idea to apply the principle more widely to economics and wealth distribution.

So how does the Pareto Principle relate to Programming?

Bug squashing

This is all very well and good, you might be thinking – but why should you care if you're a developer?

Well, the 80/20 rule also applies to various areas of programming as well. Think of it this way: 80% of bugs can be solved by fixing just 20% of the problems that cause bugs.

So instead of tackling each bug as it comes, you should work to identify the bugs that are causing the most issues. When you've found those bugs, crush them, and most (around 80%) of your problems will be solved.


On a team, some members are likely to be more productive than others. Some power through their code, focus like champs, and get done in several hours what it might take another developer all day (or longer) to complete.

Because of this, it's usually the case that 20% of team does about 80% of the work.

Writing code

When you're developing a project, it typically takes about 20% of the time you've allocated for that project to complete about 80% of the work.

But of course, conversely, the remaining 20% of the project takes up the other 80% of the time you've allotted.

In other words, building out the straightforward and general parts of an app doesn't take that much time. But implementing complex functionality, fixing bugs, and solving problems – a much smaller chunk of the overall project – easily eats up way more time.

How Can the Pareto Principle Help You Be More Productive?

Alright, hopefully you understand how the 80/20 rule works. So how can you use it in your every day life? Is it applicable to people like you and me, or is it just useful to economists and mathematicians?

You can definitely apply this principle to your life to help you become more productive and focus on what's important.

If you're a manager, for example, identify the tasks and responsibilities that are most important and that will produce the most results if you handle them personally. Anything else should be delegated or eliminated from your schedule.

If you're a writer and you want to help as many people as possible, do a little research and see which of your 10 proposed topics will be the most searched for and most relevant to people. Write about those top few subjects and do a really great job on them.

If you're a freelancer and some of your clients give you more work than others, make sure you nurture those relationships and take care of those clients (as, you guessed it, they'll probably be responsible for around 80% of your income).

So hopefully now you see how focusing on the most important, most relevant, most impactful ~20% of the stuff you're responsible for can generate the greatest outcome.

And while this distribution may not always be exactly 80%/20%, you get the idea. A small amount of causes are often responsible for a large percentage of the outcomes.

What's the Difference Between the Pareto Principle, Pareto Distribution, and Pareto Efficiency?

The Pareto Principle, as we've discussed in this article, refers to the observation that a small number of causes are responsible for a large number of outcomes.

The Pareto distribution refers to the mathematical distribution itself - that, for example, 80% of the land in Italy was owned by 20% of the people. This distribution is observed in many different fields such as economics, math, business, and so on.

The Pareto distribution is a power law distribution in statistics, which means that, in a functional relationship between two quantities, when one quantity is affected or changes, the other changes proportionately and relative to that initial change.

For example, if you double the length of the side of a square, the area of that square will increase four times.

And finally, Pareto efficiency refers to a situation where all parties concerned are in the best possible state, and none of them could become better off without detracting from the others.

For example, if three people are sharing a cake, they reach a state of Pareto efficiency if the cake is divided into three equal parts and distributed among them. None of them could have a larger piece of cake, because this would mean that one of the others would have to have a smaller one.

If, however, you had a cake divided into four pieces, and you only had three people, you could, in fact, give each person a little more cake by dividing the final piece in thirds. This situation is called a Pareto improvement, because there's room to improve the state for all parties concerned without detracting from any one of them.

And that's about it! Hopefully now you understand what the Pareto Principle, or 80-20 rule, is all about. And maybe now you can use it to prioritize tasks in your day-to-day life.