CPL, CAC and LTV: how to read three metrics together, not separately
Three metrics alone do not answer any question about money. I’ll analyze how CPL differs from CAC, why LTV without a deadline is meaningless, how to combine them into one solution, and what numbers should be considered the norm for the Russian market.
Three abbreviations that appear side by side in reports and are almost never related to each other. Individually, each of them does not answer any question about money: CPL does not say whether the channel is profitable, LTV does not say how much you can pay for a client, and CAC without LTV is simply an expense.
None of the three metrics is a solution. A solution is the relationship between them and the period in which it pays off.
1. CPL and CAC: the difference that is constantly being erased
CPL - lead cost: the person left a contact. CAC - customer cost: the person paid. In between is the work of the sales department, and this is where what looked like a cheap channel often becomes expensive.
| Channel | CPL | Conversion to payment | CAC |
|---|---|---|---|
| A | 1 500 ₽ | 4% | 37 500 ₽ |
| B | 4 000 ₽ | 18% | 22 200 ₽ |
Channel A looks three times more effective based on the orders report. In terms of money, it is one and a half times worse. The numbers are approximate, but the ratio is typical for cases when cheap applications come from broad targeting or from general requests.
Hence the rule: CPL cannot be used for channel shutdown decisions. It is suitable for diagnostics - to understand what has changed in advertising - but not for drawing conclusions about money.
2. LTV without a deadline is not a metric
The question “what is our LTV” is incorrect until the horizon is named. The answer “forty thousand” can mean both accumulated revenue for three months and a forecast for the client’s entire life, and these are two different numbers with different degrees of confidence.
It's practical to think like this: we take a cohort, look at the accumulated revenue per client by the third and sixth month. This is money that has already happened, it can be protected. Mechanics - in analysis cohort analysis, finished file with triangles - in cohort template.
Predictive lifetime LTV is also needed, but it has a different role: it’s good for strategic conversations and not good for deciding how much to pay per click tomorrow.
3. LTV to CAC ratio and what it means
| LTV / CAC | What does this mean | What to do |
|---|---|---|
| less than 1 | Every client brings a loss | Stop scaling, deal with conversion |
| 1–3 | The economy is thin, there is no reserve | Work with repeat sales and sales conversion |
| 3–5 | Healthy Range | Scale up while tracking ROI |
| more than 5 | Most often underinvestment | Check whether you are giving the market to competitors |
The last line is counterintuitive and therefore important. An eight to one ratio usually doesn't mean great marketing, but rather that the channel isn't being scaled out of caution. While you are skimming the cream, someone is taking away the volume.
Norms for niches - in LTV/CAC benchmarks, calculation - in calculator.
4. The fourth digit, without which the first three are lying
CAC payback period: how many months it takes until the client returns what it cost to attract him.
The LTV to CAC ratio can be great, but the business is suffocating. If a client pays for itself in fourteen months, then every ruble invested in growth goes out of circulation for more than a year. With rapid scaling, this ends in a cash gap with a formally healthy unit economy.
The guideline used in subscription models: payback of up to twelve months is considered working, up to six is considered comfortable. For a business without external money, the threshold is stricter.
5. All this is calculated by channel, not on average.
The average CAC for a company is a figure for a report, not for a decision. It consists of a channel with a CAC of twenty thousand and a channel with a CAC of sixty, and on average the result is a healthy thirty-five.
The worksheet looks like this: row - channel, columns - expense, applications, CPL, conversion to payment, CAC, LTV on the selected horizon, ratio and payback period. Eight columns, after which the decision to disable or scale is made by itself.
It is convenient to assemble it in unit economics calculator, and the cost per lead by channel is preliminarily calculated in CPL calculator.
6. What to fix first if the economy doesn't add up
Order by leverage, not by obviousness.
The first is the conversion from application to payment. It stands between CPL and CAC and multiplies everything on the right. An increase in conversion from 4% to 6% reduces CAC by one and a half times without a single change in advertising.
The second is repeat purchases. They move LTV, and LTV sets the ceiling for the allowable CAC. This is where retention and reactivation work, not new channels.
Third is the composition of the channels. It's cheaper to disable a bad line than to improve it.
And only the fourth is a reduction in CPL. The most obvious move and usually the weakest: all competitors are working against you in the auction at once, and the winnings rarely exceed ten to fifteen percent.
7. Summary
CPL - advertising diagnostics. CAC - customer price. LTV is the ceiling of what you can pay for it. The solution is based on the ratio of LTV to CAC and the payback period, and all this is calculated by channel.
If you take one thought away from the article, let it be this: between CPL and CAC is sales department conversion, and most often it is the real lever.
Related materials: unit economics, cohort analysis, CPL benchmarks, unit economics calculator.
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