CPA
読み方：C-P-A
Cost Per Acquisition. The average cost to acquire one conversion (lead, sale, signup, etc.). CPA = Ad Spend ÷ Conversions. A key efficiency metric for evaluating marketing channel performance. Should always be benchmarked against LTV.
What is CPA
CPA (Cost Per Acquisition) tells you what it costs to get one conversion—one contact form submission, one free trial signup, one purchase. It's the basic efficiency metric for performance marketing.
CPA Formula
CPA = Total Ad Spend ÷ Number of Conversions
Example: $5,000 in ad spend generating 25 leads = $200 CPA
Setting a Target CPA
Target CPA should be derived from LTV (customer lifetime value):
Target CPA = LTV × Gross Margin × Payback Period Fraction
If LTV = $10,000 and gross margin = 50%, you can afford up to $5,000 in acquisition cost and still break even in year one. A $200 CPA in this case is extremely profitable.
CPA vs. Related Metrics
- • CPC (Cost Per Click): Cost per link click
- • CPM (Cost Per Mille): Cost per 1,000 impressions
- • CPA (Cost Per Acquisition): Cost per conversion—the most business-relevant metric
Never evaluate CPA in isolation without understanding the LTV of what you're acquiring.