Customer Acquisition Cost Audit
Calculate blended customer acquisition cost, optional gross profit payback, and separate channel comparisons from period matched inputs.
How the CAC audit works
Enter marketing spend, sales costs, tool costs, and overall new customers for the same acquisition period. You may also enter monthly ARPU, gross margin, and LTV. Add channel rows when you want separate spend per customer comparisons.
The calculator adds the three overall cost categories once and divides that amount by overall new customers. Each channel CAC uses only that row’s spend and customer count. Channel results do not feed into the overall total.
Payback divides blended CAC by monthly ARPU times gross margin. LTV to CAC is shown only when an LTV is entered and CAC is positive. Zero customer counts leave spend visible and the corresponding CAC unavailable.
Use matching periods for overall costs and customers. Channel comparisons depend on the spend and customer attribution you enter. The calculator does not verify source records or determine whether an attribution method is correct.
Step by step
- Enter overall acquisition costs and new customers for one period.
- Optionally enter monthly ARPU, gross margin, and LTV.
- Add independent channel comparisons and review each result.
Worked example
Example inputs for one acquisition period: marketing spend 10,000 USD, sales costs 5,000 USD, tool costs 1,000 USD, 80 new customers, monthly ARPU 100 USD, gross margin 80%, and optional LTV of 4,000 USD.
Total acquisition cost is 16,000 USD, blended CAC is 200 USD, payback is 2.5 months, and LTV to CAC is 20. A separate channel row with 2,000 USD spend and 10 customers has a channel CAC of 200 USD. The channel row is not added to the overall total.
When to use this calculator
Use this calculator to add marketing, sales, and tool costs for one acquisition period and compare the total with customers acquired in that same period.
Add channel rows for separate spend and customer comparisons. Enter optional monthly ARPU, gross margin, and LTV to see the related payback and ratio calculations.
Common input mistakes
Do not compare costs from one time window with customers attributed to another. That changes CAC even when the underlying spend is unchanged. State your period and attribution method when comparing results.
Do not add channel rows to the overall total a second time. They are separate comparisons and may overlap or use different attribution. A channel result is not a recommendation to increase or cut spending.
CAC formulas
Total acquisition cost = marketing spend + sales costs + tool costs
Blended CAC = total acquisition cost ÷ overall new customers
Channel CAC = entered channel spend ÷ entered channel new customers
Monthly gross profit contribution per customer = monthly ARPU × (gross margin percentage ÷ 100)
Payback months = blended CAC ÷ monthly gross profit contribution per customer
LTV to CAC = entered LTV ÷ blended CAC, when CAC is greater than zero
Overall costs and new customers should refer to the same acquisition period. Channel rows are independent comparisons and are not added to overall totals. Payback is calculated only when both monthly ARPU and gross margin are entered. It uses them as a simplified contribution estimate and is unavailable when the contribution is zero or cannot be represented. LTV is optional. A zero CAC makes the LTV to CAC ratio undefined rather than infinite.
Scope and limitations
This calculator summarizes entered acquisition costs and customer counts. Overall marketing, sales, and tool costs should cover the same period as the overall new customer count. Channel rows are independent comparisons, are not included in the overall total, and may not reconcile with it. The model does not verify attribution, cost allocation, customer quality, or source records. Payback treats monthly ARPU multiplied by gross margin as a simplified gross profit contribution. It excludes cohorts, changing ARPU or margin, expansion, refunds, billing timing, and cash collection. LTV to CAC is undefined when CAC is zero. Nonfinite or unsupported derived values are withheld.
Key terms
- Total acquisition cost
- The sum of entered marketing spend, sales costs, and tool costs for the acquisition period.
- Blended customer acquisition cost, CAC
- Total acquisition cost divided by overall new customers from the same period. It is undefined when the count is zero.
- Channel CAC
- Channel spend divided by new customers entered for that channel. This row is a separate comparison and is not added to the overall total.
Related analysis
LTV CAC Ratio compares customer lifetime value with acquisition cost. Subscription ROI models a recurring subscription cost against an entered benefit. CAC Audit answers a narrower question about acquisition spending in one period.
Use the channel rows as separate comparisons alongside the blended total. They are not added to the total automatically and may use different attribution methods.
FAQ
What costs are included in total acquisition cost?
Add marketing spend, sales costs, and tool costs for the same acquisition period, then divide by new customers from that period. The total includes each of the three entered categories once. It is an estimate based on your chosen cost scope.
How should I interpret the channel rows?
Each channel row divides its entered spend by its entered new customers. These are separate comparisons. They are not automatically summed into the overall total and are not guaranteed to reconcile with it. The result depends on your attribution and period definitions.
How are payback and LTV to CAC calculated?
When both monthly ARPU and gross margin are entered, payback months divide blended CAC by their estimated monthly gross profit contribution. LTV to CAC divides the optional entered LTV by blended CAC. Payback does not require LTV. The LTV ratio is undefined when CAC is zero.
Which acquisition period should I use?
Match marketing, sales, and tool costs to the same acquisition period used for the overall new customer count. A different window or customer attribution changes the comparison. Channel rows use their own spend and customer inputs.
Does the result tell me which channel to scale?
It is a simple comparison of entered spend, new customers, monthly ARPU, and gross margin. It does not assess whether a channel is sustainable, profitable, or suitable for a business. Review the underlying period and attribution choices separately.
Related tools
LTV CAC Ratio focuses on lifetime value relative to acquisition cost. Subscription ROI compares a recurring cost with an entered time based benefit. These tools use different inputs and answer different questions.