How to Calculate Cost Per Acquisition
Calculate Cost Per Acquisition (CPA). Monitor efficiency at the campaign level.
Formula
Spend / Conversions
CPA
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Cost Per Acquisition (CPA) is a marketing metric that measures the total cost of acquiring a specific conversion—such as a signup, a trial, or a purchase—within a specific campaign. Unlike CAC, which looks at the ‘Whole Customer’ and includes salaries and overhead, CPA is typically focused on ‘Media Spend’ only. It is calculated by dividing the total campaign cost by the number of conversions achieved. CPA is the ultimate benchmark for campaign-level efficiency; it tells you exactly what you are paying for an ‘Action.’ To remain profitable, your CPA must be lower than the ‘Average Order Value’ (for e-commerce) or the ‘Initial Contract Value’ (for SaaS). By monitoring CPA across different ad sets and platforms, growth teams can ruthlessly cut underperforming ads and double down on the creative and targeting strategies that deliver the lowest cost per result. It is the primary lever for scaling paid acquisition without blowing the budget.
Worked example
Using the defaults – $5,000 of ad spend producing 100 acquisitions – CPA comes out at $50.
That figure is only as meaningful as the definition of “acquisition” behind it. If those 100 are trial signups and a fifth convert to paying, the cost of a customer is not $50 but $250. CPA measures the cost of a tracked action; it says nothing about what that action is worth.
CPA and CAC are not the same number
This site has a separate CAC calculator, and the difference is not cosmetic – it shows up in both terms of the fraction.
The numerator differs. This page asks for total ad spend. CAC asks for total sales and marketing cost, which pulls in salaries, agency retainers, software and commissions. For most teams that is a substantially larger number than media spend alone.
The denominator differs too. This page counts acquisitions, which can be any conversion you choose to track: a lead, a signup, an install. CAC counts new paying customers only.
The practical result is that CPA is almost always the smaller and more flattering figure, and the two are not interchangeable in a board deck. Use CPA to compare the efficiency of individual campaigns and channels. Use CAC when the question is whether the business can profitably acquire a customer at all – that is the number that belongs next to LTV.
Try asking Statspresso
“CPA for non-branded search.”
Benchmarks
CPA benchmarks are only meaningful relative to the value delivered by the acquired customer. A $200 CPA for a $2,000 ACV SaaS customer is excellent; the same $200 CPA for a $300 AOV e-commerce customer is challenging. Always calculate: CPA < LTV × target marketing efficiency ratio.
Tier | Benchmark | What It Means |
|---|---|---|
E-commerce | 10–20% of AOV | CPA should not exceed 15–20% of average order value for first-order profitability. |
SaaS | < 1/3 of LTV | A CPA below 1/3 of LTV gives you a 3× return — the minimum sustainable ratio. |
Mobile apps | $1–$5 install | Varies by app category; games run higher, utility apps run lower. |
Lead gen | < CPL × 5 | If closing 20% of leads, CPA should be < 5× your cost per lead. |
Frequently asked questions
CPA vs CAC?
CPA is often campaign-specific for a specific action; CAC is the total cost to acquire a customer.
Should I set a maximum CPA?
Yes, your max CPA should be based on your LTV to ensure you aren't overpaying for users.
How to lower CPA on Facebook Ads?
Focus on 'Broad' targeting and letting the algorithm find the cheapest conversions for you.
Does CPA include software costs?
Generally no; CPA refers strictly to media spend per conversion event.
Is CPA better than CPC?
Yes, CPA is a 'bottom-funnel' metric that measures results, not just traffic.