CPA Calculator
Calculate Cost Per Acquisition from ad spend and conversions, and check profit against your revenue per sale.
Campaign Parameters
Profit & Margin Bridge
Industry CPA Benchmarks
Benchmarks are illustrative industry averages for paid search/social acquisition costs — actual CPA varies widely by niche, region, and funnel. Click a value to apply it as your CPA input.
How CPA (Cost Per Acquisition) works
CPA (Cost Per Acquisition, sometimes called Cost Per Action) measures how much you spend, on average, to earn one conversion — a sale, signup, lead, or install. The core formula is: CPA = Total Ad Spend ÷ Number of Conversions. Rearranging that same relationship lets you solve for spend (Spend = CPA × Conversions) or for the number of conversions you can expect from a budget (Conversions = Spend ÷ CPA).
CPA alone doesn't tell you whether a campaign is profitable — that depends on how much each conversion is worth. This calculator compares your CPA against the revenue you earn per conversion to show profit per acquisition, overall margin, total net profit, and ROAS (return on ad spend, i.e. revenue ÷ spend). A campaign with a "low" CPA can still lose money if revenue per conversion is lower still, and a "high" CPA can be perfectly healthy if the resulting sale is valuable enough. All calculations run locally in your browser — nothing is sent anywhere, and the current inputs are encoded into the page URL so you can copy the link to share an exact scenario.
Built and maintained by Meet Shah · Last updated
What this tool is used for
- Working out cost per acquisition from spend and conversions.
- Solving for the spend a conversion target implies.
- Checking CPA against revenue per sale to see whether it is profitable.
- Comparing two channels on cost per acquisition.
- Producing a cost figure that can be set directly against revenue per sale.
Frequently Asked Questions
- What does it solve for?
- Any one of the three variables from the other two — CPA from spend and conversions, the spend needed for a conversion target, or the conversions a budget should produce at a known CPA.
- How does CPA relate to ROAS?
- Through revenue per conversion. CPA is what you pay to acquire a sale; dividing revenue per conversion by CPA gives ROAS. CPA is the more useful frame when order values are consistent, ROAS when they vary.
- What is the difference between CPA and CAC?
- CPA is usually per conversion event on a channel — a purchase, a signup, a lead. CAC is fully loaded across all channels including salaries and tooling, per genuinely new customer. CAC is always the larger number.
- Is profit per conversion the whole story?
- No — it uses revenue per conversion, not margin, so it does not subtract cost of goods. A positive figure here means the sale beat its acquisition cost; whether it beat the cost of the product is a separate question.
- How should I use the industry benchmarks?
- As orientation, not a target. CPA scales with customer value, so SaaS and finance sit far above retail for good reason. What matters is your own CPA against your own margin, not against another industry's average.
- Why does my CPA rise as I spend more?
- Because the cheapest, highest-intent audience is reached first. Scaling means bidding into progressively colder inventory, so a CPA that looked healthy at £1,000 a month usually does not hold at £10,000.
Common errors and gotchas
- Comparing CPA across channels without comparing the quality of the acquisitions.
- Counting a conversion that is not a sale, which makes the figure incomparable.
- Ignoring the attribution window, which changes the conversion count materially.
- Comparing CPA against revenue rather than against contribution margin.
- Mixing time periods between the spend and the conversion figures.