The Math Behind The 5-Hour Rule: Why You Need To Learn 1 Hour Per Day Just To Stay Relevant
This is the no. 1 law for the future of work.
Author’s Note: This article was written over 60 hours with love and care using the blockbuster mental model.
Knowledge has to be improved, challenged, and increased constantly, or it vanishes.
—Dr. Peter Drucker
Three years ago, I coined the term The 5-Hour Rule after researching the most successful, busy people in the world and finding that they shared a pattern: They devoted at least 5 hours a week to deliberate learning.
Since then, I’ve preached The 5-Hour Rule to more than 10 million readers. The reason I keep writing about it is two-fold:
I believe it’s the single most critical practice we all can adopt to ensure our long-term career success.
Almost no one takes this rule as seriously as they should.
Recently, I’ve realized that The 5-Hour Rule is more than just a pattern. It’s more like a fundamental law in our current age of knowledge.
And it’s backed up by basic math and a growing body of research…
Here’s The Simple Math Behind The 5-Hour Rule
Let’s assume that it took you 5,000 hours to master your field. To put this number into context, it takes about 6,400 hours of class time and studying to get a 4-year degree.
After all of this learning, you’re a happy pumpkin. You feel prepared for your profession. You’re armed with the latest and greatest skills.
But, here’s the thing…
Every second that passes by, the knowledge in your head becomes a little bit outdated, and, therefore a little less valuable. Just like a new car you buy becomes less valuable the second you drive it off the lot.
We all know this intuitively. And we also know the knowledge in our heads is becoming outdated more and more rapidly because we’re in the midst of an information explosion. 80–90% of all the scientists who have ever lived are alive today, for example.
But, did you know that there is a whole field of researchers that have discovered creative ways to measure the rate at which knowledge becomes outdated? I will dive into this research later in the article, but for now, let’s safely assume that it takes 10 years for half the facts in a given field to be proven wrong or improved on. In other words, after 10 years, 50% of the facts in the field would be outdated. This is a realistic number for many of today’s fastest-moving fields.
Ok. So, let’s explore what this means for those 5,000 hours of learning you did.
Put simply, it means this…
Of course, you wouldn’t learn all of those hours all at once. If you spread out the learning, you’d need to learn 5 hours per week, 50 weeks a year, just to stay up to date.
This math does not even include two important facts:
The people we are competing with for jobs and opportunities are spending more and more time updating their skills.
We naturally forget a lot of what we learn. These two factors mean that we’d need more than 5 hours per week in our thought experiment.
Bottom line: These numbers show that you probably need to devote at least 5 hours a week to learning just to keep up with your current field—ideally more if you want to get ahead.
If you don’t yet believe just how critical The 5-Hour Rule is to your life and career, consider this your wake-up call. I’m ringing an alarm bell for you, your colleagues, and your loved ones, so you can take action NOW before it’s too late.
Similar to a frog in gradually warming water, once you truly feel the pain of not updating your skills, it’s already too late to jump. The water is boiling.
Now that you understand the basic math behind the 5-Hour Rule, let’s dive into the underlying research and trends that are driving it so you understand the urgency of those numbers…
The 2 Fundamental Trends Driving The 5-Hour Rule
On April 19, 1965, Gordon Moore, co-founder of Intel, published an article in Electronics magazine that identified the most important phenomenon in the technology world. At its core was the observation that the number of components on an integrated circuit would double every year (updated to two years a decade later). Based on this observation, Moore predicted that computer power would balloon while costs would plummet.
The phenomenon is called Moore’s Law, and 53 years later, it still proves true. It predicted that huge workstations that filled entire rooms would eventually turn into personal computers and mobile phones. It predicts quantum computers in the future and computers that are so small they are invisible to the eye. Every technologist knows the power of Moore’s Law and factors it into their plans for the future.
This is the explanatory power of a fundamental trend in an industry.
When it comes to the future of work, there are two equally important trends that everyone should know, yet few people are aware of. They are:
Half-Life Of Knowledge: The rate at which knowledge is becoming outdated is predictable and growing exponentially (read on for the research). Therefore, just to stay relevant in the wake of this rapid evolution, we need to keep updating our knowledge.
Law Of Increasing Learning: Professionals en masse across the world are increasing how much time they put toward learning (read on for the research). Given that we are competing in a global economy for jobs, clients, and customers, we need to at least match others just to stay in the same place.
These two fundamental trends are much more than interesting theoretical points. They are practical, applicable—and most importantly, they’re affecting all of us right this moment, whether we recognize it or not.
Before I share how to apply these trends, let me explain them a little more.
Fundamental Trend #1: Your knowledge becomes more and more outdated every single day
It takes 50 years to get a wrong idea out of medicine, and 100 years a right one into medicine.
—John Hughlings Jackson, British neurologist
In his book The Half-Life of Facts: Why Everything We Know Has An Expiration Date, researcher Samuel Arbesman says:
It turns out that facts, when viewed as a large body of knowledge, are just as predictable [as uranium and other elements in their rate of decay]. Facts, in the aggregate, have half-lives: We can measure the amount of time for half of a subject’s knowledge to be overturned. There is science that explores the rates at which new facts are created, new technologies developed, and even how facts spread. How knowledge changes can be understood scientifically.
For example, if you’ve got liver disease and go to a doctor who graduated more than 45 years ago, half of that doctor’s original information is probably wrong at this point.
In another study featured in The Half-Life Of Facts, two surgeons found that half of the facts in surgery also become false every 45 years.
On a day-to-day basis, it doesn’t feel like our knowledge is becoming outdated, but consider some of the startling facts that show how off this intuition is:
Periodic Table. If you learned about the periodic table as a high school student in 1970, you were told there were 106 elements. Students today are taught that there are 118. So over the last 50 years, the decay rate of this basic fundamental knowledge of chemistry was 10%.
Number of Species. In 2017, 85 new plant and animal species were discovered. Amazingly, scientists estimate that 90% of species have yet to be discovered. It is estimated that we have only discovered .00001% of all microbial species on the planet. That’s one-thousandth of one percent.
Psychology Replication Crisis. If you studied the field of psychology in 2010, you would’ve been exposed to the top 100 studies. In 2015, researchers attempted to replicate those studies and fewer than 50% got the same results!
Smoking. Not that long ago, some of the biggest tobacco salespeople were doctors, dentists, and nurses. This vintage ad would be so crazy as to be illegal in today’s world.
Diet. In the 1980s, bacon, butter, and eggs were considered three of the worst foods you could eat for your heart. Now, many argue that they are healthy.
In the 1970s, a burst of new research on the half-life of knowledge was done by information scientists. Much of this research measured the decay by how long it takes for the citation of an average paper to end. Using this method, they found the following decay rates:
Now, consider that the fundamentals of medicine, chemistry, and psychology are slow-moving compared to new and fast-moving professional fields that are critical today:
Social media management
Driverless car engineering
YouTube content creation
Online course creation
Most of these professions barely existed 15 years ago. My personal experience backs this up…
In 1998, I co-founded a web development company. Today, many sites are created with programming languages and tools that simply didn’t exist 20 years ago. Back then, I only designed and tested sites for desktop computers. Now, we have tablets and smartphones.
When I went to undergrad business school and took entrepreneurship classes, I was taught to spend hundreds of hours creating in-depth, heavily researched business plans. Nowadays, entrepreneurs are taught NOT to do business plans and instead focus on talking to customers and using lean startup principles.
Fifteen years ago, online writing was an addendum to print magazine and newspaper articles. Now, it is the other way around. And the skillset that’s needed to be an online writer (for people reading on a smartphone after having seen your article on social media) is completely different than writing for a captive audience that has subscribed to your publication.
You’ve probably had similar experiences as these in your own field.
A Harvard Business Review article brings this into focus even more, concluding that the skills currently acquired during college stay relevant only for five years. But the solution isn’t to skip education; in fact, the same article states that:
Finally, the decay rate of knowledge is multiple phenomena wrapped into one. Understanding that these separate phenomena exist helps us understand how fundamental the trend of knowledge decay is:
Data, facts, information, and knowledge are all growing exponentially. With the advent of the Internet Of Things, more precise measurement tools, and online tracking, the amount of data about us and our world is growing. As a result, researchers have more data from which to derive scientific facts. The tools of science are subject to Moore’s Law. Better tools mean that science progresses faster.
The number of scientists in the world is growing rapidly. Ninety percent of all the scientists who have ever lived are alive today.
The number of people creating and sharing ideas is growing exponentially. 30 years ago, the main people creating ideas were scientists, intellectuals, and thought leaders. With the advent of social media, millions of people are regularly creating and sharing their lessons learned.
We can perform exponentially more complex calculations. As a result of Moore’s Law, the calculations per second that we can perform are growing. Each advance in computation allows us to understand the complexity of the world at a deeper level and solve whole classes of problems that were previously unsolvable.
We are forgetting what we know. Finally, we have the Forgetting Curve, which shows that we humans forget nearly everything we are exposed to over time without reinforcement.
Bottom Line: Learning in today’s information environment is like trying to bail water out of a leaking boat. We have all this knowledge, but it’s quickly losing value. And to make it worse, we don’t even know when a piece of knowledge expires. It’s not like we get an email notifying us: “Hey, that thing you learned three years ago? It’s not true anymore.”
The end result is that we operate with false ideas and we stop getting results. Then we have to backtrack and troubleshoot to find out what out-of-date knowledge and skills might be responsible for the poor results.
The 10,000-Hour Rule shows us that it takes an incredible amount of time and effort to be world-class at anything. The half-life of facts shows us that it takes an incredible amount of diligence to stay great in a rapidly changing field. In some ways, learning is like lifting weights. It takes a lot of effort to put on muscle. Then, we need to keep working out (all be it less hard) to keep that muscle on.
The good news is that different bodies of knowledge have different decay rates. And there are extremely useful bodies of knowledge that stay just as relevant or become even more relevant as time goes by. This is why I co-founded the Mental Model Of The Month Club and spend several hours per week studying the most useful and universal mental models that won’t go out of date for an especially long time.
Fundamental Trend #2: You are competing against people who are learning more and more
According to Our World In Data, the average person in developed societies has been spending more and more time learning in formal settings over the last two centuries. The chart below shows the astonishing growth over the last 200 years. The years of schooling have gone from 2 years to 20 years in many developed countries.
For example, between 1940 and now, the percentage of people who have graduated college in America has gone up by 8x. Amazingly, between 1997 and 2017, the college graduation rate in China went up by 10x.
The same holds true with informal learning outside of traditional institutions, which accounts for 70 to 90 percent of all learning. Podcasts, videos, articles, games, and digital courses give people the ability to learn almost anything online for free.
It’s crazy to consider that 15 years ago smartphones, YouTube, and podcasts didn’t even exist! Given that the average person’s work commute is 54 minutes, instead of listening to the radio or a Walkman, people can listen to the best knowledge humanity has ever created.
This is significant to the 5-Hour Rule because the value of knowledge is relative and operates based on the law of supply and demand. If you have a useful skill, but tons of other people have it too, then you won’t be able to command a premium for it.
Bottom line: If other people are learning more, then you have to learn just as much as them to stay relevant. If you stand still, you will fall behind. If you’ve been in your current job awhile, you might not be aware of how far you’re falling behind. But if you try to transition to a new field or re-enter the market after a break, you’ll quickly realize that your skills are outdated.
Hopefully, this combination of basic math, common sense, and these two key trends has convinced you to take action on the 5-Hour Rule. If so, here’s how to start…