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CPA (Cost Per Acquisition), or Cost Per Acquisition, is the average amount invested in advertising to achieve a conversion — whether it’s a customer, a lead, a sale, or another defined goal. It is calculated by dividing the total ad spend by the number of conversions obtained.

How to calculate CPA

Formula: CPA = Total Ad Spend / Number of Conversions.

Example 1 — Lead as conversion: A consulting company spent R$4,000 on Google Ads and generated 40 qualified leads. CPA = R$4,000 / 40 = R$100 per lead.

Example 2 — Sale as conversion: An online store spent R$8,000 on Meta Ads and made 160 sales. CPA = R$8,000 / 160 = R$50 per sale.

How to define the ideal CPA for your business

The ideal CPA is calculated based on LTV (Lifetime Value) — the total value a customer generates over the relationship with the company. The rule of thumb: sustainable maximum CPA ≤ LTV × Profit Margin / 3.

Example: Average ticket R$500, 4 purchases per year, 2 years as a customer. LTV = R$4,000. With a margin of 40%: maximum CPA = R$4,000 × 40% / 3 = R$533 per customer. If the CPA is below this value, the campaign is profitable.

CPA by segment — Brazil reference

For high-ticket B2B services, the average CPA per lead is R$80–300 and per sale R$500–2,000. For digital marketing and agencies, the CPA per lead is R$50–200. Fashion e-commerce has a CPA of R$15–50 per sale. Education and courses range from R$80–200 per sale. Real estate can reach R$2,000+ per sale.

CPA vs. CPC — the main difference

The CPC measures the cost of attracting a visitor (the middle of the process). CPA measures the cost of achieving a conversion (the final result). A campaign can have a high CPC but excellent CPA (because the conversion rate is high), or low CPC and poor CPA (because clicks do not convert). CPA is the convergence point between marketing and finance: when CPA is below LTV, the company grows sustainably.

How to reduce CPA

Improve the conversion rate of the landing page — more conversions with the same spend = lower CPA
Refine audience targeting — more qualified clicks convert better
Use remarketing — an audience that already knows the brand converts with a much lower CPA
Optimize the sales funnel — identify where leads are dropping off
Test different formats and creatives — more relevant ads have a lower CPA

Related terms

CPC — the cost per click that precedes CPA
CTR — high CTR reduces CPC and, indirectly, CPA
ROAS — the profitability per real invested in ads
ROI — total financial view of the investment
Conversion Rate — the divisor of CPA (more conversions = lower CPA)
Remarketing — the strategy that most reduces CPA from paid traffic
Paid Traffic — the context where CPA is the final result metric