Unit Economics Calculator (LTV / CAC)
Unit economics asks whether a single customer makes or loses you money. This calculator works out what you pay to acquire one (CAC), what one is worth over their lifetime (LTV), the ratio between the two, and how long it takes to get the acquisition cost back.
The number most businesses quote is LTV on revenue, and it is the one worth trusting least. A customer paying $149 a month for three years has generated a large revenue figure, but the part that funds your overheads is gross profit — revenue minus the cost of serving them. This sheet calculates both and puts the gross profit version front and centre, because that is the one that has to cover salaries, rent and the next round of marketing.
CAC payback deserves as much attention as the ratio. A business with a healthy 4:1 LTV:CAC and an 18-month payback is still going to be cash-hungry: every new customer ties up money for a year and a half before returning it. Growing faster makes the hole deeper before it makes it better. The ratio tells you whether acquisition works; payback tells you whether you can afford to do it at speed.
The sensitivity table holds CAC and margin fixed and moves only churn, which is usually the cheapest lever available and the one with the largest effect. At 1% monthly churn the average customer stays eight years; at 8% they stay a year. Same product, same spend, completely different business.
These figures only mean something if marketing spend, sales costs and revenue per customer are all measured over the same period and none of them are guesses. Finmap ties that spend to actual bank transactions, so CAC is built from what left the account rather than what someone remembered to log.
