Customer acquisition cost, usually shortened to CAC, answers a simple question: how much did it cost to win each new customer? The basic formula fits on one line. The hard part is deciding which costs belong in it, which customers count and which period you are measuring.
This guide gives a small B2B team a CAC worksheet it can copy, a way to split CAC by channel and a short list of checks before the number goes into a planning meeting. The worked example is hypothetical. It shows the arithmetic, not a benchmark for your business.
If the number points to a bigger question about where growth should come from, see business growth consulting.
1. The customer acquisition cost formula
CAC = total acquisition cost for a period / number of new customers won in that period.
Both halves need a definition before the division means anything. Acquisition cost is what you spent to attract, convert and close buyers who were not already customers. New customers are first-time buyers whose purchase was completed inside the same period. Renewals, upsells and returning customers belong in expansion revenue analysis, not in the CAC denominator.
Pick the period on purpose. A month is useful for spotting changes quickly but can be noisy for a small team that closes a handful of deals. A quarter is often steadier. Whatever you choose, keep it consistent so this quarter's CAC can be compared with the last one.
2. Decide what goes into the cost side
Most of the disagreement about CAC comes from the numerator. A version that counts only ad spend is easy to calculate and usually flatters the result. A fully loaded version includes everything the team spends to acquire customers. Calculate both, label them clearly and never compare one team's paid-media CAC with another team's fully loaded CAC.
| Cost line | Include in fully loaded CAC? | Notes |
|---|---|---|
| Paid media and sponsorships | Yes | Ads, paid placements, event booths |
| Sales and marketing salaries | Yes, the share spent on new business | Estimate the share for people who also handle existing accounts |
| Contractors and agencies | Yes | Content, lead generation, outbound support |
| Sales and marketing software | Yes | CRM, email, enrichment, scheduling tools |
| Commissions and referral fees on new deals | Yes | Partner and referral payouts tied to first purchases |
| New-customer discounts | Optional, record your choice | Some teams treat these as reduced revenue instead |
| Customer success for existing accounts | No | That cost belongs to retention |
| Product development | No | Unless a specific build exists only to win a deal |
Write the decision for each line next to the worksheet. The value of CAC over time depends on the rules staying the same. If you change a rule, recalculate the previous periods or note the break in the series.
3. A worked example (hypothetical)
Hypothetical example: a five-person B2B services firm reviews one quarter. It spent $6,000 on paid search, $9,000 on a part-time outbound contractor and $1,500 on software used by sales and marketing. Two founders estimate that a quarter of their combined salary time, $12,000, went to selling to new prospects. The firm signed eight new clients that quarter.
- Paid-media CAC: $6,000 / 8 = $750 per new customer.
- Fully loaded CAC: ($6,000 + $9,000 + $1,500 + $12,000) / 8 = $28,500 / 8 = $3,562.50 per new customer.
The gap between $750 and $3,562.50 is the point. A founder who sees only the first number may think acquisition is cheap, while most of the real cost is time and outside help. Neither figure is good or bad on its own. It needs to be compared with what a customer is worth.
4. Split CAC by channel
A blended CAC hides the channels that work. Once the total is stable, assign costs and new customers to a source: referrals, partners, outbound, paid search, content or events. Use the first-touch or self-reported source your CRM already stores, and be honest about deals with an unknown source.
Channel CAC is only as good as the attribution behind it. If most deals touch several channels, read marketing attribution before cutting a channel because its CAC looks high. Shared costs, such as founder time, can be split by the share of deals each channel produced, but record that it is an allocation rather than a measured cost.
Small numbers move a lot. If a channel produced two customers this quarter, one more or one fewer deal changes its CAC sharply. Look at several periods before drawing conclusions, and keep the raw counts next to the ratio.
For a closer look at what outside lead sources cost, compare against B2B lead generation cost.
5. Compare CAC with customer value and payback
CAC becomes useful when it sits next to the value of a customer. Two common comparisons:
- CAC payback period: fully loaded CAC divided by the monthly gross margin from a new customer. It tells you how many months it takes to earn back the acquisition cost.
- Customer lifetime value to CAC: the expected gross margin over the life of a customer compared with what it cost to win them.
Benchmarks for these ratios circulate widely, but they come from different industries, pricing models and cost definitions. Use your own history as the main reference. If retention is weak, a low CAC can still lose money, which is why retention belongs in the same review as acquisition.
6. Check the number before you act on it
- Are all new customers first-time buyers, with renewals and upsells excluded?
- Do costs and customers come from the same period, or did a late-quarter campaign produce deals in the next one?
- Is the cost definition the same as last period?
- Are the raw counts shown next to the ratio?
- Is there one named owner who updates the worksheet on a fixed date?
Then make one decision: keep, increase, test or cut a specific channel. Log the decision in your growth operations routine and review the effect next period. CAC is a measurement, not a strategy. Its job is to make the next spending decision clearer.
FAQ
What is customer acquisition cost?
Customer acquisition cost is the total amount a business spends to win new customers in a period, divided by the number of new customers won in that same period. It usually includes marketing and sales spend, and a fully loaded version adds salaries, contractors and software.
How do you calculate CAC?
Add up the acquisition costs for a chosen period, then divide by the number of first-time customers won in that period. Decide in advance which cost lines are included, keep the rules consistent between periods and report the raw counts next to the result.
Should salaries be included in customer acquisition cost?
For a fully loaded CAC, yes. Include the share of sales and marketing salaries spent on winning new business. Many small teams also report a paid-media CAC that excludes salaries. Label both versions clearly and do not compare one with the other.
What is a good customer acquisition cost?
There is no universal good CAC. It depends on what a customer is worth, your gross margin and how long customers stay. Compare CAC with customer lifetime value and payback period, and track your own trend over time rather than relying on a generic benchmark.
What is the difference between CAC and cost per lead?
Cost per lead divides spend by the number of leads generated. CAC divides spend by the number of customers actually won. A channel can have a low cost per lead and a high CAC if few of those leads become customers.
Not sure which channel is worth the spend?
Bring your last two quarters of acquisition costs and new customer counts. We can work through the numbers and decide which channel to test, grow or stop.
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