Latest / Solopreneur Sessions with Fexingo: One-Person Businesses, Freelancing, and Independent Work / How a Solopreneur Built a Business on One Calculator Tool
Transcript
- Lucas: So there's this solopreneur, let's call him Mike, who runs a one-person software business. Nothing glamorous — he builds simple web tools for tradespeople. And the thing that got my attention is that his entire company, which does about $280,000 in annual recurring revenue, started from a single calculator. Luna: A calculator? Like, a tool that does math? Lucas: Exactly. A pricing calculator for HVAC contractors. The kind where you input square footage, duct length, equipment type — and it spits out a recommended installation price. Mike had been a freelance web developer for years, and he noticed that his HVAC clients were constantly asking him to build little calculators for their own customers. So he thought, why not build one that works for any contractor, and sell it as a subscription? Luna: I love that. He didn't go after the whole software suite — just one specific pain point that was repetitive and painful. Lucas: Right. And the key insight was that HVAC contractors were still using paper price books or Excel spreadsheets. They knew their costs, but they were inconsistent in how they quoted customers. Some would underbid, some would overbid, and they were leaving money on the table either way. Mike's tool gave them a consistent, professional-looking quote in under a minute. Luna: What did he build it with? Did he need some complicated backend? Lucas: He built it as a web app using standard JavaScript and a simple database. Took him about three weeks, part-time. The first version was ugly — he told me the UI was 'functional at best' — but contractors didn't care about aesthetics. They cared about getting the number right and looking competent to the homeowner. Luna: So how did he get his first users? He didn't have a list of HVAC contractors sitting around. Lucas: He did something very manual. He searched for HVAC companies on Google Maps in his city — about 200 of them — and called each one. Not to pitch the tool, but to ask a question: 'How do you currently calculate your installation quotes?' He got maybe 30 people to talk to him. Half said they used paper, a third used Excel, and a few had custom software. He used those conversations to refine his pricing model. Luna: So he did customer discovery disguised as a phone survey. That's smart — and low cost. Lucas: Exactly. He set his pricing at $49 a month, flat. No per-quote fees, no tiers. He figured contractors would pay that out of pocket without needing a boss's approval. Then he offered a 14-day free trial to every person he'd spoken to. Of the 30, 22 signed up for the trial. And of those, five converted to paid in the first month — a 23 percent conversion rate on a cold call. Luna: That's a really strong signal. Usually you see 3 to 5 percent conversion from a free trial. So his discovery calls were effectively pre-qualifying the leads. Lucas: And he kept calling. Over the next 90 days, he worked through 500 contractors across three states. He'd call, ask about their quoting process, offer the free trial, and follow up personally. By the end of that quarter, he had 42 paying customers — about $2,000 a month in recurring revenue. Luna: That's the grind people don't talk about. It's not a launch on Product Hunt. It's 500 phone calls. Lucas: Right. And here's the thing — he didn't stop. He built a simple referral program: if a contractor referred another contractor, both got a month free. That brought in another 15 customers in the next six months without any additional calling. By the end of year one, he was at $3,500 a month. Luna: And all from one tool. No blog, no social media, no ads. Just a focused value proposition and manual outreach. Lucas: And that's the core of the episode today — how a solopreneur can build a sustainable business around a single utility, not a whole platform. Mike's story isn't about a genius algorithm or a viral launch. It's about identifying a narrow, painful problem, building the minimum viable version, and then doing the unglamorous work of talking to potential customers one by one. Luna: Let's talk about the numbers that made this work. What was the churn like? Because $49 a month isn't huge, but if people cancel after two months, you're dead. Lucas: Mike's churn after 12 months was under 5 percent. That's incredibly low. And the reason, he thinks, is that once a contractor starts using the calculator for every quote, they build it into their workflow. It becomes the default. If they cancel, they have to go back to their old messy process. So the switching cost, even though it's small, feels high. Luna: So the product itself creates stickiness through habit, not through lock-in. That's a great position to be in. Lucas: And he's been able to raise prices. Two years in, he bumped it to $59 a month for new customers. Grandfathered the old ones. Lost maybe two people. Then he added a premium tier at $99 that includes a customer-facing estimate page the homeowner can view on their phone. About a third of his customers upgraded. Luna: So his revenue didn't just grow from more customers — it grew from better monetization of existing ones. Lucas: Exactly. And he's expanded to two adjacent industries: plumbers and electricians. He built separate calculators for each — different parameters, different pricing norms — but the same basic engine. He did the same outreach playbook, but this time he had a testimonial from HVAC contractors. That shortened the sales cycle significantly. Luna: So what's his total revenue now? I think you said $280,000 ARR? Lucas: As of last month, yes. About $23,000 a month across all three industries. He's still a one-person operation. He uses a virtual assistant for support emails, but he handles everything else — development, sales, account management. His margins are probably 80 percent or higher. Luna: That's inspiring, but I think a lot of listeners might wonder — can this work for any B2B niche? Or is HVAC special? Lucas: It's not unique to HVAC, but the conditions matter. You need a niche where there's a repetitive, math-heavy task that people currently do manually, the people doing it are underserved by existing software because they're too small for enterprise tools, and they have a budget for a tool that costs less than $100 a month. That describes a lot of trades, but also some professional services — like freelance bookkeepers, real estate agents, independent insurance adjusters. Luna: So the playbook: identify the manual math problem, build a simple calculator, price it at an impulse-buy level, then personally sell it to 50 people. That's a pretty replicable pattern. Lucas: It is. And Mike's story is a good reminder that you don't need a complex SaaS platform with dashboards and analytics. Sometimes a single-purpose tool, executed well for a specific audience, can be a real business. Luna: Yeah, it really makes you think about what 'simple' can achieve. I know this kind of conversation is exactly why we keep this show ad-free — we want to focus on the actual mechanics, not the sponsor breaks. Lucas: Absolutely. And if you find value in these episodes, listener support is what keeps it that way. You can contribute at buy me a coffee dot com slash fexingo. No pressure, just if it's useful to you. Luna: Yeah, it helps us keep doing deep dives like this one. And now, I want to get back to something Lucas mentioned earlier — the expansion into electricians. How did that actually compare to the HVAC launch? Lucas: It was faster. Mike already had a template for the calculator, and he had a reference customer from HVAC who also did electrical work. So he built the electrician version in about a week. He then emailed his existing HVAC customers and asked if they knew any electricians. That generated 12 referrals in the first week. He called those, and six signed up for trials. Four converted. So he had his first electrician customers before he even did a cold call. Luna: So the network effect within the trades was real. Plumbers were probably similar. Lucas: Similar, but slower. Plumbers are a bit more fragmented. He ended up doing about 80 cold calls specifically for plumbers before getting his first three customers. But once he had those, the referral engine kicked in again. Now plumbers are his fastest-growing segment. Luna: So the lesson might be: start with one niche, dominate it, then use that customer base to springboard into adjacent niches. Much cheaper than starting from scratch. Lucas: Exactly. And that's the strategic insight — a single calculator can be a platform for expansion if you design it with modular parameters from the start. Mike's original code had the industry-specific logic stored in a config file, not hard-coded. So adding a new industry was just a matter of defining new inputs and formulas. That's a small technical decision that had huge business leverage. Luna: So for any solopreneur thinking about building a tool, the advice is: make the first version narrow, but make the architecture broad enough to expand later. Lucas: Exactly. And Mike's story also shows that you don't need to be a great marketer or writer. You just need to be willing to talk to people. That's a skill anyone can develop. Luna: Alright, I think we've got a solid blueprint here. Thanks for breaking it down, Lucas. Lucas: My pleasure. Until next time.