Marketing budgets are often set as a percentage of revenue, a number from last year, or whatever feels comfortable. A more useful starting point is a single figure: the maximum you can afford to pay to acquire one customer.
Working out what a customer is worth
The calculation does not need to be complicated. An illustrative example:
- Average order value: ₹4,000
- Gross margin: 50%, so ₹2,000 of gross profit per order
- Average orders per customer over two years: 2.5
Lifetime gross profit per customer is roughly ₹5,000. If the business wants to keep at least half of that as contribution, the maximum affordable acquisition cost is around ₹2,500.
That one number transforms marketing conversations. A campaign with a ₹1,800 cost per customer is healthy. A campaign at ₹3,200 is losing money on every sale, however good its click-through rate looks.
The levers that move CAC
Customer acquisition cost is the product of several smaller numbers. In a simple funnel:
CAC = cost per click ÷ (landing page conversion rate × lead-to-customer rate)
This is why small improvements compound. If conversion on the landing page improves from 2% to 3% and the close rate improves from 20% to 25%, acquisition cost falls by almost half — without paying a rupee less per click.
It also explains why pressure on media costs alone is rarely the best lever. Clicks are priced by an auction you do not control. Conversion and close rates are, to a large extent, within your control.
Payback and cash
Lifetime value is a promise; cash is a reality. A business that acquires customers profitably over two years may still run out of money in month three if it pays for acquisition upfront and earns the value slowly.
That is why I look at payback period alongside LTV:CAC. How many months of gross profit does it take to earn back what was spent acquiring a customer? Shorter payback means growth can be funded more safely.
Marginal, not average
Averages hide a dangerous truth: the next customer is usually more expensive than the last. As budgets rise, platforms reach further into less-interested audiences.
A channel with a healthy average CAC can have an unhealthy marginal CAC at the top of its budget. Good scaling decisions look at the return on the next increment of spend, not the average of everything spent so far.
Putting it to work
- Write down your maximum affordable CAC — even a rough estimate.
- Translate it into platform targets: target CPA, target ROAS or cost per qualified lead.
- Review marginal return before every significant budget increase.
- Invest in conversion and retention, because they raise the ceiling on what you can afford to spend.
Growth is not about spending less. It is about knowing exactly how much you can afford to spend — and then spending it well.