SaaS Unit Economics Calculator

Unit economics measure the revenue and costs associated with a single unit of your business — typically one customer. The core metrics are Customer Acquisition Cost (CAC), Lifetime Value (LTV), and payback period. They matter because they tell you whether your business model is fundamentally profitable at the individual customer level. A startup can grow revenue fast, but if it costs more to acquire a customer than that customer will ever generate in profit, the business loses money on every sale and growth only accelerates losses.

A healthy LTV:CAC ratio is 3:1 or higher, meaning each customer generates at least three times what it costs to acquire them. Below 3:1 typically means acquisition is too expensive relative to customer value. A ratio of 1:1 means you are breaking even on each customer with no margin for overhead. Above 5:1 can actually indicate under-investment in growth — you could be spending more on acquisition to grow faster. The sweet spot for most SaaS businesses is 3:1 to 5:1.

CAC payback period = Customer Acquisition Cost / (Monthly Revenue per Customer x Gross Margin %). For example, if CAC is $5,000, monthly ARPU is $500, and gross margin is 75%, the payback period is $5,000 / ($500 x 0.75) = 13.3 months. This means it takes about 13 months to recover the cost of acquiring that customer. A payback period under 12 months is considered excellent for SaaS. Under 18 months is acceptable. Over 18 months means you need significant capital to fund growth.

Simple CAC divides total sales and marketing spend by the number of new customers acquired. Fully loaded CAC also includes salaries, tools, overhead, and any other costs associated with the acquisition process. For example, if you spend $100,000 on ads and $200,000 on sales team salaries to acquire 60 customers, simple CAC is $1,667 (ads only) but fully loaded CAC is $5,000 (ads + salaries). VCs prefer fully loaded CAC because it reflects the true cost of growth, not just the marketing budget.