CPA — cost per acquisition — is what one new customer costs you in marketing spend. (Looking for the accounting qualification instead? Different CPA — this is the marketing metric.) It’s the number that turns “the campaign felt good” into arithmetic.
CPA Calculator (Cost Per Acquisition)
Spend ÷ customers acquired — with an optional LTV input for the ratio that decides everything.
The formula
CPA = Total Marketing Spend ÷ Customers Acquired
Count full spend — ads, tools, agency fees, creative — and count customers, not clicks or leads. A cheap lead who never buys is not an acquisition; mixing the two is the metric’s most common corruption.
Worked example
| Campaign spend | $6,000 |
| New customers | 120 |
| CPA | $50 |
| LTV (say) | $150 |
| LTV:CPA | 3:1 |
The only benchmark that matters
A $50 CPA is meaningless alone — brilliant for a $500-lifetime-value customer, ruinous for a $40 one. The judgment lives entirely in the ratio against lifetime value, which is why the calculator computes it and why the full treatment lives in our LTV/CAC calculator (CAC is CPA’s fuller cousin, loading in sales costs too). Practical discipline: compute CPA per channel, not blended — a healthy average routinely hides one channel printing customers and another burning cash, and the split is where the decisions are.
FAQ
What is the CPA formula in marketing? Total marketing spend ÷ customers acquired in the period. Spend includes ads, tools and fees — not just media.
What is a good CPA? One comfortably below customer lifetime value — many businesses target LTV:CPA of 3:1 or better. There is no universal dollar benchmark.
CPA vs CAC — what’s the difference? CPA usually measures a campaign’s or channel’s acquisition cost; CAC typically loads full sales and marketing cost company-wide. Same logic, wider net.
Should CPA count leads or customers? Customers. Cost per lead is a separate metric — blending them flatters campaigns that generate cheap, non-converting leads.