Cost Per Acquisition (CPA) Calculator
Calculate your cost per acquisition (CPA) to measure how much it costs to gain one paying customer through a marketing campaign.
How to use this tool
- Enter total campaign cost, number of conversions (acquisitions) and total revenue from conversions in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your cost per acquisition (cpa) and the full breakdown beneath it.
⚠ This tool provides general estimates for education only and is not financial, tax or legal advice. Figures may not reflect your situation — verify with a qualified professional.
Formula
CPA = Total Campaign Cost / Number of Conversions
ROAS = Total Revenue / Total Campaign Cost
Revenue per Conversion = Total Revenue / Conversions
How it works
Cost Per Acquisition (CPA) measures the average cost to convert a prospect into a paying customer, calculated by dividing total campaign spend by the number of successful conversions. It is one of the most important metrics in performance marketing for evaluating campaign efficiency.
This calculator also provides Return on Ad Spend (ROAS) as a quick profitability check, showing how many dollars of revenue are generated per dollar spent. A ROAS above 1 means the campaign generated more revenue than it cost, though profitability also depends on product margins.
Worked example
E-commerce Campaign Spending $5,000
- Total campaign cost = $5,000, Conversions = 100, Total revenue = $15,000.
- CPA = $5,000 / 100 = $50 per acquisition.
- ROAS = $15,000 / $5,000 = 3x.
- Revenue per Conversion = $15,000 / 100 = $150.
Each new customer costs $50 to acquire, and the campaign returns $3 in revenue for every $1 spent (ROAS = 3x).
Common mistakes to avoid
- Dividing total spend by leads or clicks rather than by actual paying customers, producing a cost-per-lead figure far lower than the true CPA.
- Omitting agency fees, creative production costs, and platform fees from total campaign cost, understating CPA and overstating campaign efficiency.
- Comparing CPA across campaigns that define conversion differently (free-trial signups vs. paid subscribers), making the comparison meaningless.
Key terms
- Cost Per Acquisition (CPA)
- The average cost incurred to acquire one new paying customer through a marketing or advertising campaign.
- Conversion
- A desired action completed by a user, such as making a purchase, signing up, or downloading an app.
- Return on Ad Spend (ROAS)
- Revenue generated per dollar spent on advertising; a ROAS of 3 means $3 revenue for every $1 spent.
- Customer Acquisition Cost (CAC)
- Similar to CPA but typically includes all marketing and sales costs across all channels to acquire one customer.
Frequently asked questions
- What is a good CPA?
- CPA must be benchmarked against customer lifetime value (LTV). A common rule is CPA < LTV / 3 for sustainable unit economics. A $100 CPA is excellent for a $10,000 product but unsustainable for a $50 product.
- How is CPA different from CPL?
- CPL (cost per lead) measures the cost to generate an interested prospect. CPA measures the cost to generate a paying customer. CPA = CPL / Conversion Rate from Lead to Customer, and is always equal to or higher than CPL.
- How can I reduce CPA without cutting spend?
- Improve conversion rates at each funnel stage, tighten audience targeting to reach higher-intent users, or reallocate budget toward channels with historically lower CPA.