The most important question in any business that acquires customers is simple: does the lifetime value of a customer exceed the cost of acquiring them? If not, growth makes losses worse. This tool gives you the exact ratio — and tells you what to do with it.
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This is a live preview of the LTV:CAC Calculator — the same tool available to all subscribers.
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Every business that actively acquires customers faces the same fundamental question: is the commercial value of each customer relationship greater than the cost of establishing it? If the answer is yes, growth is accretive — acquiring more customers creates more value. If the answer is no, growth is destructive — acquiring more customers accelerates losses. The LTV:CAC ratio answers this question with a single number.
LTV — Customer Lifetime Value — is the total gross profit a business can expect from a typical customer relationship over its duration. CAC — Customer Acquisition Cost — is the total marketing and sales cost required to acquire one new customer. The ratio of the two determines whether the acquisition model is viable, whether there is headroom to invest more in growth, or whether the business needs to either reduce acquisition costs or increase lifetime value before scaling.
LTV must be calculated on gross profit, not revenue. If a customer spends £750 per year and your gross margin is 45%, the annual gross profit from that customer is £337.50. Using revenue LTV (£750) would overstate the true value by more than double and lead to systematic overspending on acquisition. The LTV:CAC Calculator applies your gross margin to the LTV calculation, so the ratio reflects commercial reality rather than a revenue-inflated view of customer value.
Payback period is the number of months required to recover the CAC from the gross profit generated by a new customer. A payback of 4 months means that by month 5, the customer is generating net positive value to the business. A payback of 18 months means the business is funding 18 months of customer relationship before breaking even on the acquisition investment.
Shorter payback periods are always preferable, but the importance varies by business model. A subscription business with predictable retention can sustain longer payback periods because the future value is more certain. A project-based business with unpredictable repeat purchase behaviour needs shorter payback because there is more uncertainty about whether the customer will return to generate the expected lifetime value.
Customer churn — the proportion of customers who do not return each year — directly determines customer lifespan and therefore LTV. At 10% annual churn, average customer lifespan is 10 years. At 20% churn, it is 5 years. At 40% churn, it is 2.5 years. The relationship is not linear — moving from 30% churn to 20% churn adds 3.3 years of average customer lifespan and increases LTV by 50%. Moving from 20% to 10% adds a further 5 years and doubles LTV again.
This means that retention investment typically generates a higher commercial return than acquisition investment for most businesses above the minimum viable LTV:CAC threshold. A 20% reduction in churn improves LTV by 20%, which improves the LTV:CAC ratio by 20%, and may unlock the ability to increase CAC — which can accelerate growth without worsening commercial efficiency.
An LTV:CAC ratio of 14:1 looks excellent. And it is — but it also signals something important: the business is being very conservative with acquisition spend. At a 14:1 ratio, the business could increase CAC to £400 and still maintain a 4:1 ratio — a strong commercial position. The constraint is not unit economics; it is acquisition budget.
The tool makes this explicit. When LTV:CAC is above 5:1, the report tells you the maximum CAC at which a 3:1 ratio would be maintained — the commercial ceiling for acquisition spend. This converts a ratio into an actionable budget number rather than a validation metric.
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