B2B CAC: how to calculate customer acquisition cost

B2B customer acquisition cost (CAC) is all sales and marketing costs over a period divided by the number of new customers won in that period. Spend 600,000 in a quarter, win 10 customers, and CAC is 60,000. A healthy B2B model has a lifetime value of at least 3 times CAC. Most companies report CAC too low because they leave out salaries, tools and ramp.

Sounds simple, but most B2B companies forget half the costs. Here is the full calculation and the most common misses.

What is the formula for CAC?

The base formula is straightforward:

CAC = total sales and marketing costs / number of new customers

Spend 300,000 on sales and marketing over a quarter and win 10 new customers, and your CAC is 30,000. The number only becomes useful if the numerator actually contains everything. It rarely does.

Which costs get forgotten most often?

Most people count ad budget and maybe sales salaries. Then it stops. An honest CAC calculation also includes:

• Salaries including payroll taxes for everyone who works on sales and marketing, part time included. The founder's selling hours count too.
• Tools and licenses. CRM, email tools, data sources, analytics platforms.
• Content and agency costs. Freelancers, designers, consultants.
• Commissions and bonuses.
• Ramp and recruiting. The cost of hiring and training salespeople lands in practice on customer acquisition.
• Events and travel. Trade shows, customer dinners, sponsorships.

Miss these items and your real CAC can be twice the one you report.

What is fully loaded CAC and why does it matter?

Fully loaded CAC is the number with all the items above included, not just direct campaign costs. The difference is rarely small:

It is the fully loaded number that decides whether your business model holds. Pricing, margins and growth rate all rest on knowing what a customer actually costs, not what the ad account shows.

How often should you measure CAC?

Quarterly is enough for most companies between 11 and 100 employees. Monthly gets noisy when you win few customers per month. Measure per channel too, because the average often hides the fact that one channel carries the whole load while another burns money.

Also account for the lag. Costs you take in January often produce customers in April. With long sales cycles, compare the costs to the customers one sales cycle later.

Why does reactivating old leads lower your CAC?

Here is the biggest lever that few people calculate. Every lead in your CRM is already paid for. You spent ad money, event costs or sales time to get the contact, and a new B2B SaaS lead costs $249 to generate, blended across channels (First Page Sage, 2026). Yet many leads are never followed up: when HBR's researchers tested 2,241 US companies, 23 percent never answered a web inquiry at all (HBR, 2011).

When you wake a dormant lead and it becomes a customer, the acquisition cost is essentially just the cost of the follow up itself. No new ad spend, no new list, no new data enrichment. That drops your average CAC immediately, and it is often the fastest path to more customers without a bigger budget. The hard part is timing: knowing which old lead has a reason to talk now. That is where buying signals come in, such as a new manager, a funding round or a hiring push, and it is the kind of monitoring an AI GTM agent like Revexa's Leo does across both known contacts and new companies.

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Frequently asked questions

What is a good CAC in B2B?

It depends entirely on customer value. The rule of thumb is that lifetime value (LTV) should be at least 3 times CAC. A CAC of 60,000 is excellent if the customer is worth 300,000 over their lifetime.

How do you calculate CAC for B2B SaaS?

Use the same formula, fully loaded sales and marketing cost divided by new customers, and pair it with CAC payback: CAC divided by monthly recurring revenue per customer times gross margin. A customer with 5,000 in MRR at 80 percent gross margin and a CAC of 60,000 pays back in 15 months. Payback matters in SaaS because the cash goes out long before it comes back.

Should you include salaries in CAC?

Yes. A CAC without salaries is a marketing number, not a business number. Calculate it fully loaded with payroll taxes.

How does CAC differ between new and reactivated customers?

A reactivated customer only carries the cost of the follow up, because the lead itself is already paid for. In practice, CAC for reactivated customers can be a fraction of CAC for entirely new ones.