The metric Cost Per Acquisition (CPA) shows exactly how much you spend to get one conversion or one customer through your marketing efforts. It’s a fundamental KPI for performance-driven campaigns, letting you judge whether you’re paying too much for each result.
A lower CPA signals greater efficiency and more cost-effective acquisition, while a higher CPA may mean you’re paying too much, your targeting is loose or competition is fierce.
Formula
The formula to calculate CPA is:
Where:
- Total Cost = the full amount spent on the campaign
- Conversions = the number of successful actions (sales, sign-ups, leads)
- CPA = cost incurred to acquire each action or customer
For example, if your campaign spend is $3,000 and you generated 150 conversions:
Your average cost per acquisition is $20.
Why CPA Matters
CPA gives you a direct handle on the cost of acquiring customers or leads. Knowing your CPA helps you:
- Gauge efficiency: Are you converting for less than you’re willing to pay?
- Allocate budget: Shift funds toward channels or campaigns with lower CPA
- Set targets: Establish acceptable CPA thresholds relative to customer value
- Compare performance: Understand how different ad platforms or campaigns stack up
Example
An online retailer runs a Facebook Ads campaign with a spend of $4,500 and receives 300 conversions. Plugging the numbers in:
The result: each conversion cost $15. This figure can then be compared with your average order value or lifetime value to judge profitability.
Tip
Track CPA alongside related metrics like Conversion Rate (CR) and Return on Ad Spend (ROAS). A low CPA is good, but only if those conversions lead to value.