Customer Acquisition Cost Per-Unit Formula
Learn how to calculate average customer acquisition cost per new customer from advertising, payroll, and other acquisition expenses.
Customer acquisition cost (CAC) estimates the average amount spent to gain one new customer during a reporting period. Calculating CAC helps a business track acquisition efficiency, compare periods consistently, and evaluate results alongside revenue, margin, and retention measures.
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Customer Acquisition Cost per New Customer
Where:
Add all costs used to acquire customers during the period, then divide that total by the number of genuinely new customers gained in the same period.
Variables Explained
| Variable | What It Means | Unit |
|---|---|---|
| advertisingSpend - Advertising Spend | Paid advertising costs for the reporting period, such as search, social, display, print, or sponsored placements. | currency |
| salesAndMarketingPayroll - Sales and Marketing Payroll | Wages, commissions, benefits, and similar payroll costs attributable to new-customer acquisition. | currency |
| otherAcquisitionCosts - Other Acquisition Costs | Relevant acquisition expenses such as agency fees, events, campaign tools, creative production, and lead-generation costs. | currency |
| newCustomersAcquired - New Customers Acquired | The number of genuinely new customers acquired during the same reporting period as the costs. | number |
| totalAcquisitionCosts - Total Acquisition Costs | The combined acquisition-related expenses included in the calculation. | currency |
| customerAcquisitionCost - Customer Acquisition Cost | The average acquisition cost for one new customer. | currency |
Step-by-Step Calculation
Identify the reporting period
Choose a month, quarter, year, or campaign period. All cost inputs and the new-customer count must use that same period.
reportingPeriod = consistentPeriod
Total advertising spend
Include the paid advertising costs that relate to acquiring new customers in the selected period.
advertisingSpend = paidMediaCosts
Add acquisition-focused payroll
Include only the portion of sales and marketing payroll, commissions, and benefits that is reasonably attributable to acquisition activity.
salesAndMarketingPayroll = acquisitionPayrollCosts
Add other relevant acquisition costs
Include other costs that support new-customer acquisition according to the business's consistent cost-allocation method.
otherAcquisitionCosts = agencyFees + campaignTools + events + creativeCosts
Calculate total acquisition costs
Combine the included advertising, payroll, and other acquisition expenses.
totalAcquisitionCosts = advertisingSpend + salesAndMarketingPayroll + otherAcquisitionCosts
Calculate CAC per customer
Divide total acquisition costs by the number of new customers. The result is the average cost per new customer.
customerAcquisitionCost = totalAcquisitionCosts / newCustomersAcquired
Example: Monthly customer acquisition cost
Add advertising and payroll
$5,000 + $3,500
$8,500
Add other acquisition costs
$8,500 + $1,500
$10,000
Divide total costs by new customers
$10,000 / 100
$100
State CAC
CAC = $100 per customer
$100 per customer
Final Result
Estimated customer acquisition cost: $100.00 per new customer, based on $10,000 in included acquisition costs and 100 new customers.
Assumptions
- ✓All entered costs and new-customer counts cover the same reporting period.
- ✓Only costs connected to acquiring new customers are included.
- ✓Each new customer is counted once, even if the customer makes multiple first-period purchases.
- ✓The business uses the same definition of a new customer each time it calculates CAC.
- ✓The result is a blended average across included channels, products, and customer segments.
Limitations
- !CAC does not show whether acquired customers are profitable, retained, or likely to purchase again.
- !Long sales cycles can create a timing mismatch between when costs are paid and when customers are counted.
- !Attribution choices may change which channel or cost receives credit for a new customer.
- !A blended CAC can hide meaningful differences between campaigns, products, regions, and customer segments.
- !Cost allocation for shared payroll, software, and events may require internal judgment.
Common Mistakes to Avoid
Dividing monthly costs by customers acquired over a different period, such as a quarter.
Including renewals, returning buyers, or leads instead of genuinely new customers.
Excluding sales commissions, agency fees, or acquisition-focused payroll in one period but including them in another.
Counting one customer more than once when they buy multiple products or make repeat first-period orders.
Comparing channel CAC figures that use different attribution rules.
Treating a low CAC as sufficient without considering customer margin, retention, and revenue.
Related Formulas
Frequently Asked Questions
What is the formula for customer acquisition cost?
CAC equals total acquisition costs divided by the number of new customers acquired. Total costs can include advertising, acquisition-focused sales and marketing payroll, and other relevant acquisition expenses.
How do I calculate CAC per customer?
Add the acquisition costs for a consistent period and divide by the number of genuinely new customers gained in that same period.
Should sales and marketing payroll be included in CAC?
It can be included when payroll is attributable to winning new customers. Use a documented and consistent allocation method, particularly when employees also support existing customers.
Do I include agency fees and marketing software in CAC?
They may be included when they directly support acquisition. Apply the same inclusion policy across reporting periods to make comparisons more meaningful.
Why is my CAC higher than my advertising cost per conversion?
CAC may include payroll, commissions, agency fees, events, creative costs, and other acquisition expenses in addition to paid media spend.
Can CAC be zero?
It can be zero only when included acquisition costs are zero and at least one new customer is acquired. A zero result may also indicate omitted costs, so review the inputs.
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