What is cost per acquisition (CPA)?
Cost per acquisition is what you pay, on average, for each conversion, whether that is a signup, demo request or sale. It is the workhorse metric of paid performance, but it only means something in context: a CPA is good or bad relative to what the acquisition is worth. Always compare it to the value of the conversion, not to a universal benchmark.
How this calculator works
The formula: Cost per acquisition = ad spend ÷ conversions Conversion rate = conversions ÷ clicks Cost per click = ad spend ÷ clicks ROAS = (conversions × revenue per conversion) ÷ ad spend
Clicks and revenue per conversion are optional. Add them to see the full efficiency picture, from click through to return.
CPA vs CAC
CPA usually measures a single campaign-level action; CAC measures the fully-loaded cost of a paying customer across all sales and marketing. A signup CPA only becomes useful once you know what share of signups turn into customers, which links CPA to CAC.
How to reduce CPA
- Raise conversion rate. More acquisitions from the same clicks cuts CPA directly.
- Improve targeting. Stop paying for actions from poor-fit accounts.
- Lower cost per click. Better ad relevance reduces the input cost.
- Build organic rankings. Owning converting terms organically lowers blended CPA.
Frequently asked questions
How do you calculate cost per acquisition?
CPA = ad spend ÷ conversions. $5,000 producing 25 conversions is a $200 CPA. Add clicks for conversion rate and cost per click, and revenue per conversion for ROAS.
What is the difference between CPA and CAC?
CPA is the cost of a defined conversion at campaign level; CAC is the fully-loaded cost of a paying customer across all sales and marketing. CPA is a campaign metric; CAC is a company metric.
What is a good CPA for B2B SaaS?
No universal figure; it depends on what the conversion is worth. Keep CPA below the value of the conversion (close rate × deal value for a lead, or below LTV for a customer).
How can I reduce CPA?
Raise landing-page conversion, tighten targeting, improve ad relevance to lower CPC, and build organic rankings for your best converting terms.