CPA: Cost Per Acquisition
The cost of acquiring one customer or conversion event through paid advertising.
Formula
Why it matters
CPA is the most direct measure of campaign efficiency relative to your business goal. Unlike ROAS, CPA works even when revenue is deferred — making it the standard metric for lead generation, trial signups, and subscription businesses.
How to improve CPA
Optimise landing pages to improve conversion rate, tighten audience targeting to reduce irrelevant clicks, and test lower-funnel bidding strategies (Target CPA in Google Ads, Cost Cap in Meta).
Benchmarked against your LTV. Sustainable CPA is typically below 30% of first-year customer value.
Prooflytics tracks CPA automatically from your connected sources and flags it in your daily briefing when it moves significantly.
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Calculate CPA from spend and conversions
CPA
CPA = Total Spend ÷ Conversions
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Estimate CPA from CPC and conversion rate
Estimated CPA
CPA = CPC ÷ (Conversion Rate / 100)
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Frequently asked questions
What is the difference between CPA and CPL?
CPA (Cost Per Acquisition) measures the cost to acquire a paying customer. CPL (Cost Per Lead) measures the cost to generate a lead. For e-commerce, CPA is typically used; for B2B lead gen, CPL is the first-stage metric.
What is a target CPA?
Target CPA is a Google Ads smart bidding strategy where you set the average CPA you want to achieve and Google's algorithm automatically adjusts bids. It requires at least 30–50 conversions per campaign per month to work reliably.
How does CPA relate to LTV?
A healthy CPA is typically below 30% of your first-year LTV. If LTV is $500, a sustainable CPA is below $150. If CPA exceeds LTV, the campaign is unprofitable regardless of ROAS.