Let me tell you a story about a business in the education space. They operate in an incredibly competitive market. Their margins are razor-thin.
That is why it is critical they understand their acquisition costs and their CAC to LTV ratio. Today, let’s focus on the CAC.
Even a small shift in CAC can turn a winning customer into a money-loser.
The same math applies to you, especially if you’re running a business with tight margins.
The Shortcut You’re Probably Taking in Calculating CAC
A common approach is to calculate CAC as total ad spend, or total out-of-pocket marketing spend, divided by the number of new customers.
On the surface, this feels simple and practical. If you spent $10,000 on ads and got 100 customers, the CAC is $100. As a quick proxy, that might seem fine.
The problem is that it is incomplete. And incomplete here means it could have detrimental effects.
What Your CAC Really Includes
True acquisition cost is more than just your ad spend. It includes all costs connected to marketing. This means:
- Ad spend
- Salaries of the marketing team
- A portion of management or owner salaries if they spend time on marketing
- Content writers, designers, or freelancers
- Software and tools used for marketing
Too blurry? Let’s make it tangible. Imagine you spent $10,000 on ads. Your marketing coordinator costs $4,000 a month. You personally spend about 20 percent of your time on marketing, which is worth another $2,000 when allocated. Then there is $500 for software and $1,500 for freelancers. That means your real marketing spend is not $10,000. It is $18,000.
If those same 100 customers came in, your CAC is $180, not $100. That is a very different picture, and it has real implications when you start comparing CAC to customer lifetime value.
You Can’t Win With CAC Alone
CAC only matters when you put it in context. The right benchmark is your gross margin-based lifetime value. Lifetime value on its own is not enough, because it includes revenue that never becomes profit. If your clients are worth $600 each in gross margin, then with a CAC of $100, you look great. But if the real CAC is $180, your profitability shrinks quickly. With thin margins, that difference can decide if you scale or if you bleed cash.
Can You Flip CAC Below Zero?
Here is where it gets really interesting. What if you could bring CAC below zero?
We have seen this happen. If you have built an organic channel, for example, a podcast, YouTube channel(s), or newsletters, you can monetize these with sponsorships or advertising revenue. In some cases, that may even boost the marketing value of the channel.
In those cases, we have seen CAC turn negative.
For every new client you acquire, you could also generate income along the way. That changes the game entirely. It means marketing becomes infinitely scalable in theory. You are not just reducing costs. You are creating a flywheel where you get paid to acquire more clients.
The Bottom Line for You
Understanding CAC is about seeing the true costs behind your customer acquisition, and then making decisions with accurate numbers. The shortcut might be OK for the 80/20, but it can be misleading and potentially dangerous.
If you know your true CAC, compare it against your gross margin-based LTV, and explore ways to make marketing channels work for you financially, you set yourself up for real and sustainable growth.
And who knows. With creativity and the right channels, you might even find yourself in the enviable position of being paid to get new clients.
If you’re in the agency world, I recently put together a full guide on scaling from $1M to $5M without burning out, covering the hidden financial traps. You can read it here:
The CFO’s Guide to Scaling an Agency
Want to talk about how to define CAC in your business? Just send me a DM.
And let me know what finance matters keep you up at night – so I can help you sleep better in the next update!
Running an e-commerce brand? See how we support e-commerce finance, from cash flow to margins.
