Cost Per Acquisition (CPA) Calculator
Calculate your cost per acquisition from ad spend and conversions. Optionally add LTV to see your max profitable CPA and LTV:CAC ratio.
Spend in a given period
Customers or sales in same period
Optional — for CPA vs. LTV analysis
Use the LTV Calculator if unsure
Sets your max profitable CPA = LTV × margin
Return on ad spend target (e.g. 3 = $3 revenue per $1 spent)
How to Calculate CPA
CPA = Total Ad Spend ÷ Number of Conversions. If you spent $5,000 and acquired 42 customers, your CPA is $119.05. CPA tells you the efficiency of your acquisition channels, but it doesn't tell you whether that CPA is profitable — for that, you need to know your Customer LTV.
What Is a Good CPA?
There is no universal "good" CPA — it depends entirely on your LTV. The only meaningful CPA benchmark is: CPA < LTV × Gross Margin. That formula gives you your max profitable CPA — the highest you can pay per customer and still break even on gross profit. A $200 CPA is excellent if your LTV is $1,000 and awful if your LTV is $150.
Use the LTV Calculator to find your customer lifetime value, then plug it in above to find your max profitable CPA. For the full LTV:CAC framework, see the Unit Economics Calculator.
CPA vs. ROAS — What's the Difference?
ROAS (Return on Ad Spend) measures revenue generated per dollar spent on ads — typically used for ecommerce where each conversion has a direct revenue value. CPA measures the cost to acquire one customer — more common in lead generation, SaaS, and subscription businesses where each customer has a long-term value. Both metrics matter: ROAS optimizes the immediate sale; CPA optimizes long-term customer economics.
Frequently Asked Questions
How do I reduce my CPA?
Lower CPA comes from: better targeting (reach people more likely to convert), higher-converting landing pages and ad creative, tighter audience segmentation to eliminate wasted spend, improving offer clarity, and testing new channels. Incremental improvements to conversion rate have a compounding effect on CPA — doubling your conversion rate halves your CPA on the same spend.
What is the difference between CPA and CAC?
CPA (Cost Per Acquisition) is typically a campaign-level paid media metric — what you paid per conversion in a specific ad campaign. CAC (Customer Acquisition Cost) is a broader business metric that includes all marketing and sales costs across all channels divided by all new customers. CAC is more comprehensive and includes organic, sales team, content, events — not just paid ads. For unit economics analysis, CAC is the right metric.
Should I optimize for CPA or LTV?
Optimize for both simultaneously. Minimizing CPA alone can lead you to acquire customers who churn quickly (low LTV). Maximizing LTV:CPA ratio is the right objective — you want to acquire high-value customers at the lowest possible cost. Use CPA as an efficiency signal and LTV:CPA ratio (which mirrors LTV:CAC) as the profitability signal.
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