CACvsLTV:TheRealProfitabilityEquation
First-order profitability is often a misleading metric for growth. The question is not whether today's sale made money, but whether this customer relationship will make money over time.
The First-Order Profitability Myth
First-order CAC often exceeds initial profit. This is not necessarily a problem. Profitability relies on repeat behaviour over time.
A customer acquired at £30 who spends £25 on order one looks like a loss. But if that customer orders four more times over 18 months, the £30 CAC becomes excellent value.
The Customer Journey Reality
Growth is only sustainable if LTV eventually covers CAC plus overheads within a safe payback window. The first transaction is the beginning of a relationship, not the end of a measurement.
The Real Customer Journey
What matters in the customer journey:
- • Loss-making first orders: Common and acceptable with proven repeat behaviour
- • 60-90 day repeat dependency: Most value comes from second and third purchases
- • Variance by product cohort: Not all products create equal repeat behaviour
When LTV Justifies Losses
Accepting first-order losses is justified when:
- You have proven repeat purchase data (not projections)
- LTV:CAC ratio exceeds 3:1
- Payback period is under 90 days
- Cash runway can absorb the delay
"We can afford a higher CAC on Cohort A because they buy 3x in Year 1. We cannot afford the same CAC on Cohort B who rarely return."
Understanding Payback Periods
Payback period is the time it takes to recover customer acquisition costs:
Healthy: Under 90 Days
Cash returns quickly. Can reinvest into more acquisition. Lower risk.
Risky: Over 120 Days
Cash is tied up too long. Growth strains working capital. Higher risk of growing broke.
Valuation depends on the 3:1 ratio, but survival depends on payback velocity.
LTV Cohort Analysis
Not all customers are equal. Different products, channels, and entry points create cohorts with very different LTV profiles.
- • Subscription starters: High LTV, predictable repeat
- • Discount seekers: Low LTV, one-time buyers
- • Hero product buyers: Moderate LTV, gateway to catalogue
- • Gift purchasers: Low personal LTV, but may introduce recipients
Target CAC should vary by cohort. Spending the same CAC on all customer types guarantees overpaying for low-value cohorts and underspending on high-value ones.
Strategic Agency Behaviour
When we understand LTV cohorts, agency behaviour changes:
- • Move from "efficiency" targeting to "lifetime value" targeting
- • Set CAC caps based on proven cohort LTV
- • Cap spend on slow-payback cohorts even if ROAS looks good
- • Prioritise high-retention SKUs over high-margin single-purchase products
The Cohort Question
Before setting CAC targets, ask: "What cohort does this campaign attract, and what is the proven LTV of that cohort?" The answer determines whether losing money on order one is smart investing or just losing money.
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