Your CAC/LTV ratio looks great. 3:1. Clean. Exactly where the frameworks say it should be.
What the ratio doesn’t tell you: it takes 8 months to get there.
That payback window — the time between when you spend the CAC and when the customer has returned enough revenue to cover it — is where cash goes to disappear. And most DTC brands growing at 20 to 40 percent year over year are quietly funding a working capital crisis one acquisition campaign at a time.
Here’s the Math That Doesn’t Show Up in the LTV Dashboard
If you’re spending $80K per month on acquisition and your average payback window is 6 months, you have $480K of unrecovered acquisition spend in the system at any given moment. If you grow 30% next year and increase monthly acquisition spend to $104K, that unrecovered number grows to $624K. The faster you grow, the bigger the hole.
None of that shows on your P&L. It shows on your bank statement.
I watched this play out in real time at a $40M subscription ecommerce brand. The CAC/LTV ratio was healthy. The acquisition engine was performing. But because nobody had modeled the cash timing of that payback window against the growth plan, the business was consistently short on cash even while it was consistently profitable on paper.
The Fix
The fix isn’t to stop acquiring customers. The fix is to model the cash impact of your payback window into your 13-week cash forecast — so you know exactly how much working capital your growth plan requires before you commit to the spend.
A 3:1 LTV/CAC ratio is a great marketing metric. It’s a terrible cash flow plan.
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If your growth plan is outpacing your cash, let’s model the gap.
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