Result
Repeat purchase cost
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This calculation is for informational purposes only and does not replace advice from a qualified professional. Formulas and rates may not fit your exact situation — double-check the figures before making decisions.
How it is calculated
Repeat purchase cost = retention spend ÷ number of customers with a repeat purchase. It's the same principle as CAC for new customers, just with a different spend base and customer base: this counts money spent specifically on winning back an existing audience, not acquiring a new one.
The cost of a repeat purchase is almost always noticeably lower than CAC for a new customer — the business already has a relationship with this person and data on their past purchases, so reaching them costs less than reaching a cold audience.
The gap between repeat purchase cost and ordinary CAC is a quantitative case for why retention usually beats constantly growing new acquisition: even a modest retention budget can compete on efficiency with a much larger acquisition budget.