The Most Passive Online Side Hustle I've Ever Seen
In this video Chris Koerner explains why ultra‑simple web tools—especially calculators, quizzes and generators—can generate massive passive income with minimal ongoing effort. He shows data on high‑traffic calculator sites (paycheck, calorie, mortgage, etc.) and demonstrates how to discover profitable niches using keyword tools (Ahrefs, Semrush, Google Trends). Koerner then walks through building an AI token‑cost calculator from scratch using Hostinger Horizons, detailing prompt engineering, UI tweaks, email‑capture gating, and integration of Google AdSense. He discusses monetization strategies (ads, email list value, affiliate links), domain and hosting setup, cost of using Hostinger credits, and how to replicate the process to launch multiple calculators quickly. Throughout, he emphasizes rapid shipping, low overhead, and scaling the model across dozens of niche calculators.
Chapters
Why is it that the most simple websites seem to make the most money? Is it because they do one thing really well? Is it because millions of people are searching for these things and no one else thought to build it? I don't know, but what I do know is that these simple websites that merely have a quiz, a calculator, an X, Y, or Z generator have never been easier to build. And 2 to 5 years from now, this won't be an opportunity, but right now, non-coders such as myself can vibe code simple sites like these forget about it entirely, and maybe, hopefully, possibly make hundreds or thousands or tens of thousands of dollars a month almost perfectly passively. So today I'm going to do two things. I'm going to profile a handful of these simple calculator sites that are now, thanks to AI, very easy to build. And the second thing I'm going to do is show you exactly how to build one in a niche that is likely to be high demand and profitable. And most importantly, I'm going to show you how to monetize this calculator website, because if you don't have ads on the site, it will never be monetized. And your downside is a few bucks and a couple hours of tinkering around. So let's dive in. Let's talk about calculators for a minute. Not these, but these. Boom, boom, boom, boom. This simple paycheck calculator website gets over 700,000 unique visitors per month, which if you just host ads on the site and do nothing else, makes it worth about $1.1 million. And why is it a thing? Because people want to know how much of their paycheck is actually going to end up in their bank account. So they search paycheck calculator and this guy pops up. Here's a simple calorie calculator, 456,000 organic visitors a month. So if you just build this thing, put some ads on it, it's worth 6 figures. And let me be clear, these things take no work. You don't need employees. You don't even need to invest more than an hour a week in this once it's built and running. Now I could go on and on, but we only have so much time today. A compound interest calculator, ovulation calculator, pregnancy calculator, Percentage calculator, mortgage calculator, you get the ideas. And this is not just a winner-take-all market. There's a bunch of websites that simply have mortgage calculators that get thousands and hundreds of thousands and millions of visitors. So I did a little research on how many people are searching for terms on Google or AI with the word calculator in it. And according to Ahrefs, which that's all they do, there's almost 36,000 different keyword clusters that have the word calculator in it. Now, an example of one of those could just be mortgage calculator, or it could be 15-year mortgage calculator or VA loan mortgage calculator. There's 36,000 of those things with the word calculator in it. And I don't want you to think that this is done, it's played out, all the best calculators have been built. Absolutely not, because new things are being invented, new trends are happening, people and things are changing, which also means that some of these older calculators don't get much traffic like they used to. That also happens. And guys, no pun intended, but I'm eating my own dog food here. I have this website that is a directory for pet and horse cremation and euthanasia facilities. And we added a bunch of calculators, all built with AI, to our website to get more traffic. This is our pet cremation cost calculator. Pet type, pet weight, cremation type, and location. This helps us generate leads that we can sell to veterinarians and horse cremation facilities. So I'm actually doing what we're talking about here today. But before I show you how to build a calculator, I just have to show you the Mac Daddy of all calculators, and that's the site Omni Calculator. This dude in Poland wanted to learn how to code, so he thought, I'll build a calculator so I can learn. People started visiting it, it started getting 800 downloads a day, and then he thought, why don't I put more calculators on this same website? So now he has over 3,700 custom calculators and he gets over 17 million visitors per month. He has 70 employees, and they bring in over $500,000 a month of revenue, most of that profit. Am I saying that's realistic? Absolutely not. But it's an awesome example and it's something that we can be inspired by. So I'm going to build one of these from scratch today. I'm going to use a new AI tool called Hostinger Horizons. And by the end of this video, it's going to be on the internet and hopefully making a little bit of money with ads. So the first thing you're going to do is go to hostinger.com/kerner10. Looks like that. We're going to click Start Now. We're going to choose the starter plan because we're starters. Also on the starter plan, you get up to 25 websites, which is important for this business because if one calculator works, we want, why not, 24 more calculators. Again, we can build these things in minutes, not hours. We get e-commerce built in, we get a free domain name, and we can use it to prompt with both images and voice instead of just text. So we're going to go for the 12-month plan. We're going to use code KoernerOffice. To get 10% off. Okay, we're good to go. Remember, the best tool sites, that's what we'll call these calculators, best tool sites solve a very specific problem that have high and/or growing search volume. How do we know what terms those are? What has good search volume? Okay, so you can use tools like Semrush and Ahrefs and ChatGPT, Claude, whatever to find out what some of these keywords might be. You've got like core keywords like mortgage calculator and then what they call long tail keywords, which in this case would be something like FHA loan mortgage calculator Texas. That's a long tail keyword that's obviously gonna get fewer searches per month, but will also likely have fewer competitors, which is important. The question is, where is the supply and demand imbalance? Which term or terms have more volume but fewer competitors? So what's up and coming right now? What tidal waves are happening right now that we could hop on for dear life and build a calculator around? Well, AI, health and fitness, GLP-1s, solar, green energy, protein, creatine. Side hustles are growing like crazy right now. Why? Because everyone's afraid, and rightfully so, that AI is going to steal all our jobs. So we'll have time for a side hustle and/or we'll need a side hustle to pay the bills or a full-time business. Obviously, that's the niche I'm going to go down because that's the one I know best. And I will say it's important that you choose a niche that you love and that you know. You don't have to, but it makes your endeavor more scalable, more sustainable, whether it is a calculator website or a taco truck, doesn't matter. Now I think I've whittled it down to two finalists of calculators that I wanna build. Number one is the side hustle profit calculator. I think more people are gonna be searching for that, but I don't wanna guess. I want data to show me. And number two, an AI cost calculator because anyone vibe coding, building apps, doing anything with AI, there are costs associated with it over and above the flat fees that platforms charge. They're often overaggressive. Charges that you have to pay for these tokens. In other words, the amount of data you're using when you're prompting these AI tools. It would be helpful for laymen like me to be able to calculate what the costs would be using an AI tool or a vibe coding app like Hostinger, for example. So what I'm going to do is go to Google Trends and I'm going to put these two finalists for my calculator side by side and see which one wins. Okay, well, that's an easy choice. AI cost calculator over the last 5 years is growing, growing, growing, and side hustle profit calculator is not really growing. In fact, there's very little search volume whatsoever. So it's an easy decision. Okay, so I'm going to go back to Hostinger Horizons and type in my prompt to get this calculator built. Here's my prompt. I want a simple website that will be an AI token cost calculator. It will help Vibe Coders and other people wanting to build with AI tools to be able to determine how much they will have to pay in token usage using any of the popular or obscure AI tools and LLMs out there based on publicly available token pricing. Make it look clean and simple and easy to use and don't display the result for the end user until I get their email address. Okay, let's see what it comes up with. We're gonna time it as well. It's 12:59 right now. All right, you can see it working here. A clean and professional calculator interface, 22 popular and obscure AI models with real pricing data, email collection before showing results. All emails are stored in your database. Okay, awesome. Said it better than I could have. Okay, here we are. It's been a total of 6 minutes and we have what we're looking for, an AI token cost calculator. All right, let's check it out. Let's say, let's say Claude 3 Opus. Okay, I don't like that it just says input and output tokens because I don't think that's clear enough to the average user. Now what I understand that to mean is how many tokens it uses when you prompt the AI, that's the input, and then how many tokens the AI uses when it gives you the output. Is referred to as the output token. So I just re-prompted it and said, make it more simple to use and understandable for the average layman that doesn't know what input or output tokens are and show examples on the page of how many tokens a few different prompts would be varying sizes and prompt outputs as well. So people can gauge how many tokens 1,000, for example, actually is. Okay, done. But this gave me an idea of how to make it even better. For some reason it made the user interface even more attractive as well, which I didn't even ask it to do. But I would love for people to also see how many tokens their prompt is. So this is very cool at the bottom. This is what I asked it to do, real world token examples. But how cool would it be at the top if they could type in a prompt and it could tell them how many tokens that is, and then they can use that number of tokens to get their cost calculator. Boom. So I love screenshotting specific things on these vibe coding tools. So I'm gonna do this. Drag it over here and say, okay, my reprompt. This is awesome, added screenshot, but add in a field to this section where people can type in a prompt or paste in an output from another model like ChatGPT or Claude, and your calculator will tell them how many tokens either one represents. And then at the bottom of the page, give them tips on how to reduce token usage as well. I'm thinking those tips will really help with SEO, search engine optimization, so more people can organically find the site. And I don't know if you noticed this, but I put in my original prompt that I want their email address before they see the result. That's kind of what you do when you go take like one of those dumb IQ tests. It's called a sunk cost fallacy. You spend 15 minutes taking an IQ test and by the time you go to see the result, they want your email. You are for sure going to give them your email. Now that can work here. It won't work as well because it won't take them 15 minutes to fill this out, but I want to have my cake and eat it too. I want to monetize the site both with ads and to collect email addresses because these are valuable email addresses. These are people that are gonna be using AI tools, that are gonna be vibe coding. There's a decent chance they have some money. So I can use those emails to start a newsletter, to send them my Hostinger affiliate link or whatever. All right, here's the token counter tool. I'm gonna type in something like, show me some obscure websites that are obscure calculators that make a lot of money organically. That's only 23 tokens. So then I can take that 23, I can put it up here, and if I really wanna know, then let's go to an AI tool like Claude. I'm gonna paste in that same prompt. I'm just gonna do Opus 3. Okay, there's the output. Let's go back to Hostinger. Boom. Put the output into the tool. 248. So about 10 times more than what my input was. We used Claude 3 Opus. Calculate total cost. Boom. So that cost almost 2 cents. The vast majority of about 90% of it on the output tokens, which makes sense. Now it's a little broken here because it's giving me the result before it asks for my email. It shouldn't do that. So anytime you're using a live coding tool like Hostinger, you're gonna have some hangups. That's always gonna happen 'cause it doesn't know what's in your brain, right? So what I love about Hostinger Horizon is they have like an AI tool on top of their AI tool, basically a robot that fixes the other robot. It's called Cody. I'm gonna pull this up and say, boom, I clearly did not prompt this well enough. So I'm gonna ask Cody, the AI assistant, give me a good prompt to fix my AI token cost. Tool to where it won't show the user the results until they enter in their email address. Okay, now it gave me a much more complex prompt that I can just paste right over to the main window here to be sure that it's fixed. Boom. Let's try it again. I'm just going to type in some dummy data. Boom, there it is. Look at that, look at that. It's blurred out, but I can unlock my results if I type in my email. It's perfect. Cody, you work perfectly. Thank you, Cody. By the way, why are there no Cody adults? We all knew Codys in high school, but I don't know one Cody adult other than Cody Sanchez, which is a female. Side note. Okay, now with most other vibe coding tools, if you want to edit something simple like the text, you have to prompt it again. You got to screenshot something like this and say, change the title to X, Y, or Z. But what are we talking about right now, guys? We're talking about tokens. That costs tokens. It costs you money to edit the text. It should not cost you money to edit simple things like this. So I'm not a huge fan of this subheadline, so I'm going to change it to say this. How much does your AI tool cost you? Find out here. Boom. Love it. Okay, I'm ready. Let's publish this bad boy. Big purple button on the top right. Now we're going to monetize it. So stay tuned. It'll only take a minute. While we wait for the site to be published, let's talk some real numbers on how much money you can make from these with Google AdSense. If you're unfamiliar with Google AdSense, it is like the ad platform. Any banner ad, Sidebar ad, anything like it's all Google AdSense. And I will say Google AdSense is a great starting point. It is a very low friction way of making money on the internet, but it should not be what you end with. I love Hostinger because it has a built-in integration with Google AdSense. You don't have to go through all the rigmarole on Google's website. You can just do it with a few clicks, but don't stop there. Don't be content with that because if you're getting like, let's say 10,000 page views a month. That's going to be like $30 to $100 a month. Not bad. But if you use other ad tools or if you collect emails, those emails could be worth $10 each, right? Each. How many emails could you get from 10,000 visitors a month? If you get 1%, that's 100 emails. That'd be $1,000 a month, over 10 times as much as if you just use AdSense. So we're going to show you how to use AdSense because we don't want any friction to making money, but don't be content with AdSense. Now how do we integrate AdSense? I'm just asking Horizons, please enable AdSense on my site 'cause they already have an integration. You just have to ask it to do it and it's done. Boom, your calculator is now a complete monetized tool. Done. One sentence prompt. Okay, so we need to add a custom domain to this bad boy and I chose the starter plan because it includes a free domain name, a free email and hosting as well. All right, so we just go here and what domain name do I want to connect to the site? I'm gonna type in aitokenscalculators.com, click it, go next. All right, you can see that it's a cent for the first year, which is almost free. But if I want a free one, then I can choose a.cloud domain name, which is fully free included in the starter plan that I bought. And here's what's crazy. Everything I've done so far to build the final product here cost me 4 credits on Hostinger. I have 70 for the month and I have 66 left. Looks like I gotta update this as well. 2024 pricing, nope, 2026. Boom. Now, how does my website look on the actual internet? Well, here it is published. We did it. And because we chose calculators with an S, we can add multiple calculators to our site. And with Hostinger, you can just copy and paste. You, we can copy and paste this calculator and swap out different features or functions, different niche, same looking calculator. You can share your template with other people and you can manage the domain, the SSL, everything all in one platform, one dashboard. So I've started over 80 businesses over the last 18 years. Some took me months or years to start. Many failed. This business took me minutes. If you want to win online, you got to ship. You got to ship more. You got to build. You got to post your crap. Post it to the internet. Analysis paralysis is a 4-letter word here on the Koerner Office, so don't even think about doing it. Hostinger Horizons is a great partner to the Koerner Office. They're obviously sponsoring this video, and I wouldn't choose them as a sponsor if I didn't love their product and their company. So use code KoernerOffice for 10% off, link in the description, and go build something already. We'll see you next time on the Koerner Office.
