Use CAC to connect acquisition spending with customer growth.
Define acquisition spend consistently. Depending on the purpose, CAC may include media, agency fees, sales commissions, acquisition-team payroll, software, creative production, and other direct acquisition costs.
Compare CAC with contribution margin and customer lifetime value rather than revenue alone. A customer can generate high revenue but still be unattractive if gross margin or retention is low.
Different questions need different denominators.
CAC divides acquisition spend by new customers acquired. ROAS focuses on attributed revenue from advertising, CPC focuses on clicks, CPM focuses on impressions, and conversion rate focuses on completed outcomes relative to opportunities.
Formula and calculation method.
CAC = Acquisition spend ÷ New customers acquiredDivide the sales and marketing acquisition costs included in the analysis by the number of new customers acquired during the corresponding measurement period.
See the business meaning, not just the math.
$20,000 acquisition spend and 125 new customers
Working: $20,000 ÷ 125
Result: $160.00 CAC
Interpretation: The modeled acquisition program spent an average of $160 for each new customer before considering contribution margin and retention.
$7,500 channel spend and 60 new customers
Working: $7,500 ÷ 60
Result: $125.00 CAC
Interpretation: Compare this channel CAC with a consistently defined benchmark and with the value created by customers from the same channel.
$9,600 acquisition spend and 80 new customers
Working: $9,600 ÷ 80
Result: $120.00 CAC
Interpretation: The cohort averages $120 of acquisition spend per new customer before retention and lifetime value.
Put the number in context.
Define acquisition spend consistently. Depending on the purpose, CAC may include media, agency fees, sales commissions, acquisition-team payroll, software, creative production, and other direct acquisition costs.
Compare CAC with contribution margin and customer lifetime value rather than revenue alone. A customer can generate high revenue but still be unattractive if gross margin or retention is low.
Assumptions and common mistakes.
What the calculation assumes
- Acquisition spend and new-customer counts cover corresponding periods and channels.
- Only new customers are included in the customer denominator.
- The chosen cost definition is applied consistently across comparisons.
- The calculator reports an average and does not model cohort differences.
Mistakes to avoid
- Using total customers instead of newly acquired customers.
- Excluding major sales or marketing costs from one period but including them in another.
- Comparing blended CAC with channel-specific CAC without noting the scope difference.
- Judging CAC against revenue without considering margin and retention.
What unusual inputs mean.
CAC is undefined because new customers are the denominator, so the calculator returns an error.
The result is a valid zero CAC when at least one new customer is recorded.
Leaving payroll or sales costs out of one period but including them in another makes the comparison unreliable even when the arithmetic is correct.
What this calculation leaves out.
CAC is an average based on the cost definition and customer cohort entered. It does not calculate customer lifetime value, payback period, retention, contribution margin, channel incrementality, or cohort variation. Finance and marketing teams should agree on which acquisition costs belong in the numerator before using CAC for decisions.
Questions people ask.
How do I calculate CAC?
Divide the acquisition costs included in your analysis by the number of new customers acquired in the corresponding period.
Should payroll be included in CAC?
It can be when payroll is part of the sales and marketing acquisition cost definition. The important point is to use a consistent definition.
Is CAC the same as cost per lead?
No. Cost per lead divides acquisition spend by leads, while CAC divides acquisition spend by customers actually acquired.
What should CAC be compared with?
Common comparisons include gross contribution, payback period, retention, and customer lifetime value.
Why are zero new customers invalid?
CAC divides acquisition spend by new customers, so zero customers would make the average undefined.