How to Turn Your Side Hustle Into Passive Income

[Welcome to Side Hustle #81, where Zach from Four Pillar Freedom stops by to share his experience — and tips — on how to “productize your knowledge.” We’ve covered tutoring as a side hustle before in different flavors (#14 & #74), but Zach’s approach goes beyond trading time for money … and turns his work into passive income, bringing in money while he sleeps! For those of you with specialized knowledge or expertise in a certain area, this could be a great fit for you!]


In college, I chose statistics as a major because I was good with numbers and I knew it was a lucrative field. This seemed to be a win-win: I could earn good money and enjoy my work.

It wasn’t until I graduated and actually spent some time in a 9-5 work environment that I realized I would likely never enjoy a corporate job, even if I liked the work itself. The commute, the strict schedule, the meetings, the office politics, and the performance reviews all made the job miserable.

But I eventually found that my knowledge in statistics could be lucrative in a different setting: tutoring.

Statistics Tutoring as a Side Hustle

In my senior year of college, I noticed a fascinating trend when I told other students that I was majoring in statistics. Without fail, they would reply with some version of:

“I had to take an introductory stats course during my freshman year as a requirement for my major and I hated it.”

In many cases, they said that they’d have been willing to pay for a stats tutor but that it was so difficult to find one.

This lead to my light-bulb moment: There was a high demand for people who could tutor in introductory stats, yet very few people had the knowledge to do so.

Basic supply and demand told me that I could charge a high hourly rate for my time as a statistics tutor, so that’s exactly what I did. I posted ads on Craigslist and found several people within my first week who were willing to pay $30 per hour for my tutoring services.

In the months that followed, I met with people at libraries, coffee shops, and Barnes & Noble cafes and tutored them all in introductory statistics. It didn’t take long to realize that I could increase my hourly rate to $50 to $60 and most people were still happy to pay.

Trading Time for Money Has an Upper Income Limit

Statistics tutoring was a great side hustle for me. I could earn good money and I actually enjoyed helping people learn.

There was only one drawback: I was trading time for money, which meant there was an upper limit on how much I could earn.

For example, I often had two hours of free time each weekday during my senior year since I had a part-time job and classes to attend. So, if I charged $50 per hour, then the most I could earn through the week was 10 hours * $50/hour = $500.

Of course, I could increase my hourly rate even higher, but fewer people would be willing to pay this price and my income would once again hit a ceiling.

This brings up an important point: When you trade time for money, there is an inherent upper limit on how much you can earn. This applies to freelancing, consulting, day jobs, and any other scenario in which you’re trading your time for income. There is only so much time in the day.

Fortunately, there’s another way to earn income that doesn’t require you to trade your time for money: productize your knowledge.

Productize Your Knowledge

To “productize your knowledge” means to create some type of product that you can sell that encapsulates your knowledge on a particular subject.

For example, I have knowledge in statistics. When I tutored people in statistics, I provided a service. They gave me money in exchange for my knowledge.

However, I could instead create a product, such as an ebook, a course, or paid tutorials on statistics, that I could sell to people. This meant I didn’t need to directly exchange my time for money. People could simply buy my products and use them to learn about statistics on their own time without me.

So, that’s exactly what I did. I built Statology, a site that now has hundreds of statistics tutorials that people can read through on their own time. The site is monetized mostly with advertisements, which means I earn a bit of ad revenue each time someone visits the site.

The beauty of this is that I don’t have to be physically present to earn money from my statistics knowledge. I can create a tutorial on a certain topic one time, publish it, then walk away. 

Then, people on the internet can search for the topic I wrote, find an article on Statology, read through it, and in return, I receive ad revenue.

Now, instead of getting paid to help one person face-to-face, I can help hundreds of people each day and receive passive income in return. Even when I’m not actively tutoring, my website is earning income for me each day.

By productizing my knowledge, I  removed the upper limit on how much I can earn.

How to Productize Your Knowledge

There are many ways you can productize your own knowledge, including writing an ebook, creating a course, selling downloadable templates, or through writing helpful articles on a website and monetizing them with display ads.

The process for doing this is simple:

  1. Find a topic that you have unique, rare knowledge in.
  2. Create a product based on this knowledge that you can sell to people.

I’ve come across thousands of people online who are all earning income from their unique knowledge in different ways. A few of my favorite examples include:

  • One guy who is an orchestra percussionist earns money by selling courses to aspiring musicians that help them prepare for interviews and auditions.
  • One woman who lives in a camper sells books and courses on tiny living and on how to live optimally in trailers and campers.
  • One guy who is a magician sells courses and paid tutorials that explain how to do various magic tricks for beginners.
  • One woman who is a painter sells courses on how to paint better and also runs a YouTube channel that is monetized with ads.

In each of these cases, these people possess a certain knowledge in a certain field. Instead of renting out their time to provide services, they have decided to create products based around this knowledge that they can sell online at all hours of the day to earn passive income.

Get Started on Your Side Hustle!

What specific knowledge do you possess? 

Do you know a lot about statistics, organic chemistry, or some other tricky subject?

How about travel hacking with credit cards?

Or maybe certain programming language or software?

Identify some topic that you have rare knowledge in. Then productize that knowledge.


Zach quit his day job at age 25 and now earns a full-time living creating and managing profitable websites. Check out Four Pillar Freedom, where he teaches others how to build passive income and work toward financial independence!

Photo up top by Matt Ragland

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  1. Backpack Finance June 26, 2020 at 5:59 AM

    I really like to the concept of productizing your existing knowledge. It makes the side hustle so much easier than actually doing something from scratch. Your base is already there in your head. Gives me quite a few ideas now :) Thanks for sharing.


    1. Zach @ Four Pillar Freedom June 30, 2020 at 1:29 PM

      “Your base is already there in your head” – Exactly! It’s just a matter of turning that base of knowledge into something other people can consume.

  2. Liz June 27, 2020 at 7:31 PM

    Great idea! Stats was the hardest class I took while pursuing my B.S. in Accounting.

    1. Zach @ Four Pillar Freedom June 30, 2020 at 1:30 PM

      Thanks Liz! I also hear that a lot from people in similar majors who have to take at least one stats class.

  3. Caroline at Costa Rica FIRE June 28, 2020 at 5:46 PM

    Agree that productizing your knowledge can get you out of the time for money trade. That being said, you still have to sell those products, which entails a lot of different skills such as social media, online advertising, pricing, etc. I have productized some of my consulting services, and it’s great having that stream but it’s still a small fraction of my billable hours, even though I have worked with specialists to grow it. I still agree that it’s worth it to start that business, but it’s not as simple as build it and people will come.

    1. Zach @ Four Pillar Freedom June 30, 2020 at 1:31 PM

      Agree that it definitely takes work up front to productize your knowledge. Once the initial hard work is done though, it can turn into a passive income stream that pays you over and over again. It’s just a matter of committing the time to make the product at first.

  4. Tara/Sparkrental June 30, 2020 at 1:37 PM

    Great info Zach, and congrats for being able to Productize Your Knowledge! I do trade time for money but this time I feel it is on my own terms. I am social media marketing manager for a great company. For so long I have worked jobs with only one thing in mind “MONEY,” and that’s all that mattered, but I was miserable and hated it. I’ve always loved how I could create really amazing relationships with people through social media and even helped others boost their businesses just by creating the right relationships through their networks and promoting. I finally decided to make this a career and no school necessary which was a plus. I’m just good at it and have the tools. I love what I do!! Unfortunately there are way to many people selling courses, books, and lessons about social media marketing so It would be tough product to sell.

  5. Wyatt Warn July 6, 2020 at 2:27 AM

    Great points about turning your own unique skill set into something which has potential to earn profit. I could’ve definitely used you as a tutor during my first year, stats haunts me til this day. Thanks for the article, will be sharing it with some buddies who’ve been discussing side hustles.

  6. Dollartrak July 10, 2020 at 7:47 PM

    This was a really well done article. I have had this same thought about building a SaaS vs consulting. You put into words how I had always felt.

    1. Joel July 12, 2020 at 10:23 AM

      “SaaS Your Knowledge”. That’s a cool slogan :)

  7. Diane taber January 22, 2021 at 5:43 AM

    Hi we’re both trying to find a second job to do as a side hustle so we can finally get out of debt.and we can’t wait as we are both doing jobs that are both not very well paid jobs. And so it’ll take us longer to get out of debt. If we don’t get/ have a side hustle going as we’ll need this/one.