What is CAC?
Customer acquisition cost, the total sales and marketing spend required to win one new customer.
CAC = Total Acquisition Spend / New Customers Acquired
A worked example
In a month you spend Rs 1,60,000 on ads, Rs 25,000 on agency fees and Rs 15,000 on tools, and acquire 160 genuinely new customers. Your CAC is Rs 1,250, not Rs 1,000, which is what you get if you count only the media spend and quietly ignore everything else.
Why it matters
CAC is the number that decides whether growth is worth having. Every business can buy customers; the question is whether the customer is worth more than what you paid. That makes CAC meaningless in isolation and essential next to lifetime value.
A Rs 1,250 CAC is excellent for a subscription product with an Rs 8,000 lifetime value and fatal for a one-time Rs 900 purchase. The widely quoted rule of thumb is that lifetime value should be at least three times CAC, though early-stage brands often deliberately run thinner to buy growth and market position.
The other reason CAC matters is that it forces honesty about what acquisition actually costs. Businesses that track only media spend consistently understate CAC by thirty to fifty per cent, then wonder why a channel that looks profitable in the ads dashboard is not producing cash.
The nuance most people miss
Blended CAC and paid CAC answer different questions and both are worth knowing. Blended CAC divides all acquisition cost by all new customers, including those who arrived organically (it tells you what growth costs the business overall. Paid CAC isolates the customers attributable to paid channels) it tells you whether the advertising is working. A business with strong word of mouth can show a comfortable blended CAC while its paid campaigns lose money, and only the split reveals it.
Common mistakes
- Counting only ad spend and excluding agency fees, tooling, creative production and salaries
- Mixing new and returning customers in the denominator, which flatters the figure substantially
- Measuring CAC over a period shorter than your sales cycle, so the spend and the customers it produced land in different months
- Comparing your CAC to a competitor's without knowing whether they calculate it the same way. Most do not