Business Finance
Customer Acquisition Cost Calculator
Find the cost of winning each first-time paying customer. Then, if you have recurring monthly economics, see how long the contribution you keep could take to recover that cost.
Your acquisition picture
Customer acquisition cost
Start with your acquisition spend and new customers. Your cost per customer will appear here.
What would recovery take?
Optional monthly economics compare the revenue you earn with the contribution you keep.
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The method
Count acquisition costs, then recover them from contribution
Customer acquisition cost divides sales and marketing acquisition expenses by new paying customers from the same period. Include the labor, commissions, agencies and tools used to acquire those customers, without counting a cost twice. Optional payback divides unrounded CAC by monthly contribution per customer: monthly revenue multiplied by your contribution margin. The revenue-only comparison shows why ignoring serving costs can make recovery look too fast.
Example 1
The same customer: 1.5 months of revenue, 2.5 months of contribution
$12,000 of marketing acquisition costs plus $6,000 of sales acquisition costs wins 120 first-time paying customers. CAC is $18,000 ÷ 120 = $150. Each customer generates $100 a month, but a 60% contribution margin leaves only $60 after serving costs. Dividing CAC by revenue gives 1.5 months; dividing by contribution gives 2.5 months. If contribution arrives in full monthly installments, three installments are needed. This worksheet assumes the customer stays and pays; it does not forecast retention or cash collection.
- CAC
- $150.00
- Monthly contribution
- $60.00
- Revenue-only comparison
- 1.50 months
- Contribution recovery
- 2.50 months
- Full monthly contributions
- 3
Example 2
A revenue number cannot fix zero contribution
With $150 CAC, $100 monthly revenue and a 0% contribution margin, all revenue is consumed by the modeled serving costs. There is no finite contribution-based recovery, even though the revenue-only division still returns 1.5 months.
- Monthly contribution
- $0.00
- Contribution recovery
- No finite recovery
Before you calculate
Assumptions & limits
- Use one period for acquisition spending and first-time paying customers. Long sales cycles can separate when spending occurs from when customers convert. This period ratio does not establish causal attribution or align acquisition cohorts automatically.
- Include acquisition-related marketing and sales labor, commissions, media, agencies and tools. Allocate shared costs consistently and exclude retention-only spending. Customer service and fulfillment costs belong in the contribution assumption, not counted a second time as acquisition costs.
- Recovery requires both optional inputs. Monthly revenue is a recurring average, not a single purchase repeated automatically. Contribution margin is the share remaining after the serving costs you include, before acquisition spend. It may differ from accounting gross margin.
- Payback assumes constant monthly economics. It excludes churn, changing purchase frequency, taxes, discounting and actual collection timing. Full months means the count of equal monthly contributions needed, not a promised calendar date. No lifetime-value prediction or universal CAC benchmark is provided.
- All money uses USD with no conversion. Each amount accepts 0–1,000,000,000 with up to two decimals. Customers must be 1–1,000,000,000 whole people or accounts. Margin accepts 0–100% with up to two decimals.
- CAC and contribution display to cents; fractional recovery displays to two decimal months. Calculations retain unrounded values before recovery, and full monthly contributions round the exact ratio upward. Display rounding uses midpoint ties upward. A tiny positive value may display as zero; whole-period recovery still uses its exact value.
- Zero acquisition spend means no cost to recover, including when contribution is zero. Positive acquisition cost with zero contribution has no finite recovery. Zero customers is invalid because CAC has no denominator.
Keep in mind
Common mix-ups
Counting orders instead of new customers
Five orders by one returning customer are not five new acquisitions. Use first-time paying customers for CAC.
Dividing by revenue instead of contribution
Revenue must also cover serving costs. The worked comparison shows why $150 CAC needs 2.5 months of $60 contribution, not 1.5 months of $100 revenue.
Comparing different cost scopes
Ad-only cost per purchase and fully loaded sales-and-marketing CAC answer different questions. Match scope before comparing teams or periods.
Sources & calculation notes
Explains acquisition spending scope, customer counts and the distinction from ongoing support and infrastructure costs.
Documents CAC divided by monthly revenue per account times gross margin. This calculator uses the user’s explicit contribution margin and shows its assumptions rather than importing benchmark scores.
Calculation and input rules checked: . Engineering validation; no professional accounting review is claimed.