Cost per lead isn’t everything: the metrics that show whether your traffic is profitable

When someone shows me a campaign’s results, the first number that shows up is almost always cost per lead. “My leads cost $1!” Sounds great. But on its own, that number says very little about whether you’re making or losing money.

Let me show you with an example why I never judge a campaign by cost per lead alone.

An example with two campaigns

Imagine a business running two campaigns in the same month (the numbers are illustrative):

• Campaign A: spent $1,000, generated 200 leads at $5 each and closed 4 sales.
• Campaign B: spent $900, generated 60 leads at $15 each and closed 9 sales.

Looking only at cost per lead, Campaign A seems three times better. Now look at how much each sale cost:

• Campaign A: $1,000 ÷ 4 sales = $250 per sale.
• Campaign B: $900 ÷ 9 sales = $100 per sale.

The campaign with the “expensive” leads is two and a half times more efficient. If the business had cut B to put everything into A, it would have sold less while spending more.

A cheap lead who doesn’t buy is just a slower way to spend money.

The metrics I track

To know whether traffic is profitable, I look at a sequence of numbers, each one answering a different question:

• Cost per lead (CPL): how much it costs to bring in a contact. Useful for comparing similar ads, but not for making decisions on its own.
• Lead-to-sale conversion rate: out of every 100 contacts, how many buy. It shows the quality of the audience and also of your customer service.
• Customer acquisition cost (CAC): how much you spent on ads to win each customer. It’s the number from the calculation above.
• Average ticket: how much each customer spends, on average, per purchase.
• ROAS (return on ad spend): how much revenue came back for every dollar invested. A ROAS of 4 means $4 in revenue for every $1 in ads.
• Customer lifetime value (LTV): how much a customer spends with you over the whole relationship, including repeat purchases.

The calculation that decides whether it’s worth it

In the end, the question that matters is simple: is the profit a customer generates greater than the cost of winning them?

If your CAC is $100 and each customer leaves $300 in profit on the first purchase, the campaign pays for itself right away and you can invest more. If your CAC is $100 and the profit on the first purchase is $60, you may even be losing money at first. But if that customer usually comes back several times, the LTV can justify the investment.

That’s why the same CAC can be great for one business and terrible for another.

Without tracking, none of this works

All of these metrics depend on one thing: knowing which sales came from which campaigns. Without that, you’re making decisions in the dark.

The minimum I set up on any project is the Meta pixel and Conversions API, Google Ads conversions, Google Analytics and a way to record in customer service where each customer came from. That’s exactly why we created MaxMetrics, our monitoring platform, to bring all of it together in one place.

In short

Cost per lead is the start of the conversation, not the end. Before pausing or scaling a campaign, look at how much each sale cost and how much profit each customer leaves. Those are the numbers that show where your money is really working.