Unit economics: CAC, LTV, ROAS and break-even

0:00 Unit economics

Here's a scenario that catches out a lot of growing brands. The ads dashboard says return on ad spend is three. Everyone celebrates. Six months later, there's less cash in the bank than before. How? Because ROAS on its own doesn't tell you whether you're making money. In this lecture you'll learn the unit economics that do: customer acquisition cost, lifetime value, return on ad spend, break-even ROAS and a blended reality check called MER. By the end, you'll be able to answer the one question every owner cares about: should we spend more, or not?

0:42 Customer acquisition cost

First, customer acquisition cost, or CAC. It's your total sales and marketing costs in a period, divided by the new customers you gained in that period. Include ad spend, creator fees, agency or freelancer fees, tools, and a fair share of salaries. And only count new customers. Here's an illustrative example. A UK subscription box spends eight thousand pounds on ads, two thousand on creators and two thousand on tools and freelance help in a month, and gains four hundred new subscribers. Twelve thousand divided by four hundred: CAC is thirty pounds. Notice it's usually higher than the cost per purchase your ad platform shows, because it counts everything.

1:29 Lifetime value

Next, lifetime value, or LTV. It estimates the value a customer brings over their whole relationship with you. A simple version is: average order value, times purchases per year, times average lifespan in years, times margin. And please use margin, not revenue. Revenue-based LTV looks impressive and ignores what the product costs. For our subscription box: twenty pounds a month, twelve orders a year, customers stay about a year and a half, and the margin is forty percent. Twenty times twelve times one point five times zero point four gives one hundred and forty-four pounds of profit per customer.

2:12 LTV:CAC and payback

Now put them together. LTV divided by CAC: one hundred and forty-four divided by thirty is about four point eight to one. A commonly quoted rule of thumb is that three to one or better is healthy, but the right ratio depends on cash flow and how reliable your LTV estimate is. That's why you also check payback: how many months of profit it takes to earn back CAC. The box earns eight pounds of margin a month, so payback is thirty divided by eight, about three point seven five months. Here's the key idea. For a small business, fast payback often matters more than a big ratio, because cash pays the bills.

3:01 ROAS and break-even

Now ROAS. Return on ad spend is revenue attributed to ads divided by ad spend. If five thousand dirhams of ads produce twenty thousand dirhams of attributed revenue, ROAS is four. It's quick and useful, but it has three limits. It uses revenue, not profit. It depends on each platform's attribution rules. And it usually ignores repeat purchases. So how do you know if a ROAS is good? Calculate break-even ROAS: one divided by your margin. With a fifty percent margin, break-even is two. With twenty-five percent, it's four. So a ROAS of three is excellent for one business and loss-making for another. Never judge ROAS without the margin.

3:48 Example 1: Pakistani fashion label (illustrative)

Let's do the simple worked example. A Pakistani fashion label sees a ROAS of two point five on Meta. Their margin is forty-five percent, so break-even ROAS is one divided by zero point four five, about two point two. First-order profit is thin but positive. Their own store data shows around thirty percent of customers buy again within six months. So the decision is: keep scaling carefully, add a post-purchase email flow to lift repeat purchases, and track CAC and payback monthly. That's what unit economics gives you. Not a feeling. A decision with a reason.

4:30 Example 2: Riyadh coffee subscription (illustrative)

Now a more realistic scenario, with illustrative numbers. A speciality coffee subscription in Riyadh charges one hundred and twenty riyals a month, with a thirty-five percent contribution margin, so forty-two riyals of profit a month per subscriber. Last month they spent thirty-six thousand riyals, including creator fees and tools, and their store shows two hundred and forty new subscribers. So CAC is a hundred and fifty riyals. Meta reports a first-order ROAS of one point six, which looks awful against a first-order break-even of about two point nine. The team is ready to cut spend. But wait. This is a subscription. What does payback say?

5:16 Payback changes the answer

Payback is a hundred and fifty divided by forty-two, about three and a half months. And customers are staying about nine months so far, so LTV is roughly three hundred and seventy-eight riyals, around two and a half times CAC. First-order ROAS was simply the wrong lens for a subscription. So instead of cutting, the team keeps spending and focuses on the real risk: cancellations in months two and three. They improve onboarding emails and add a pause instead of cancel option. And they re-check LTV every month using cohorts, groups of customers who joined in the same month, as real retention data arrives.

6:01 Blended reality check

One more tool: blended metrics. MER, the marketing efficiency ratio, is total revenue divided by total marketing spend. And new-customer CAC is total marketing spend divided by new customers from your own store or CRM. They're blunt, but they're hard to fool, because they don't depend on any platform's attribution. Here's the warning sign to watch. Platform ROAS goes up, but MER and new customers stay flat. That usually means platforms are claiming credit for sales that would have happened anyway, not real growth. And a final reminder: ROI counts all costs and all profit, so a good ROAS can still hide a poor ROI.

6:47 Mistakes and measures

Common mistakes. Using revenue instead of margin for LTV. Comparing ROAS between businesses with different margins. Leaving creator fees, discounts and tools out of CAC. Counting returning customers as new. And projecting LTV from a few months of data with no caution. So be conservative. Cap projected lifespan until you have real data, and track cohorts. To measure success, write one line every month: CAC, payback, LTV to CAC, and MER, compared with last month. A healthy business sees CAC stable or falling as spend grows, and payback within what its cash can afford.

7:28 Recap and try this now

Let's recap. CAC counts all acquisition costs divided by new customers only. LTV multiplies order value, frequency, lifespan and margin. Payback tells you how fast cash comes back. Break-even ROAS is one divided by margin, and MER keeps platform numbers honest. Put together, they answer whether to spend more. Here's your try this now. Build the unit-economics sheet from the lesson text, fill it in for a real or imagined business, and then write two sentences: should this business scale spending, and which single assumption would change your answer if it turned out to be wrong?