Unit economics for non-finance founders

If you're a technical founder, unit economics is probably the topic you most want to skip and most can't afford to. It boils down to one question: when you acquire a single customer, do you make money or lose money on them over time? Get this wrong and you can grow your way straight into bankruptcy — every new customer deepening the hole.

CAC — Customer Acquisition Cost

What it costs, all-in, to acquire one customer: total sales and marketing spend divided by customers acquired in the same period. If you spent $10,000 on ads and content last month and got 100 customers, your CAC is $100. Founders routinely underestimate this by forgetting to include salaries, tools, and their own time.

LTV — Lifetime Value

The total profit you earn from one customer over their entire relationship with you. Roughly: average revenue per customer per month, times gross margin, times how many months they stay. The "how many months they stay" part is where churn lives — and it's why retention is an economic lever, not just a feel-good metric. A customer who stays 36 months is worth three times one who stays 12, for the same acquisition cost.

The two ratios that matter

• LTV:CAC. How much you get back for every dollar you spend acquiring. The rule of thumb is around 3:1 — three dollars of lifetime value for every dollar of acquisition cost. Below 1:1 you lose money on every customer; far above 3:1 you might be under-investing in growth.
• CAC payback period. How many months of revenue it takes to recoup the cost of acquiring a customer. Under ~12 months is healthy for most SaaS; longer means you're financing growth for a long time before it pays back, which strains cash.

Why this beats a giant TAM

A huge market with broken unit economics is a trap; a modest market with strong unit economics is a business. If each customer reliably returns three times their acquisition cost and pays you back within a year, you have a machine that turns marketing dollars into profit — and that, not a billion-dollar TAM slide, is what makes a company fundable and durable.