Sign in

Free calculator · no login

CPA calculator: work out cost per acquisition, budget or conversions

To calculate CPA, divide ad spend by the number of conversions: 900 spent for 30 completed enquiries is a CPA of 30.00 per enquiry. The calculator also works backwards. Enter a target CPA and a conversion goal to get the budget you need, or a budget and a CPA to estimate how many conversions it buys. Name the action first, because a lead, a purchase and a new customer give very different CPAs.

Free tool · runs in your browser

Calculate CPA, budget or conversions.

Choose what to solve for, then enter the other numbers. The starting values are illustrative. Nothing you enter is sent to Adlane.

Solve for

Cost per acquisition

—

Enter your values, then calculate.

CPA = spend ÷ conversions

The average spend per action you counted. Name that action (lead, purchase, new customer) before comparing campaigns.

CPA formula

CPA = spend ÷ conversionsBudget = target CPA × conversionsConversions = budget ÷ CPABreak-even CPA = gross profit per conversion

How to use the CPA calculator

  1. Choose what to solve for: CPA, budget or conversions.
  2. Define the action in plain language, then enter numbers from the same period and scope. Allow for delayed conversions: the last week of a report usually shows a higher CPA than it will once the window matures.
  3. Press Calculate. The working is shown under the result. Compare the CPA with your break-even CPA, and keep different action types in separate comparisons.

Cost per defined action: a worked example

Illustrative example: 900 in spend produces 30 completed enquiries, a CPA of 30.00. To get 50 enquiries at the same CPA you would need about 1,500; a 600 budget would buy about 20. None of this says how many enquiries became customers.

CPA examples for each calculation

The same formula answers three planning questions. All numbers are illustrative, not benchmarks.

QuestionYou knowWorkingAnswer
What is my CPA?Spend 900, enquiries 30900 ÷ 30CPA 30.00
What budget do I need for 50 enquiries?Target CPA 30, enquiries 5030 × 50Budget 1,500
How many enquiries will my budget buy?Budget 600, CPA 30600 ÷ 30About 20 enquiries
What is my CPA with no conversions?Spend 300, conversions 0Division by zeroUnavailable

Where to find CPA in Google Ads and Meta

Google Ads: add Cost, Conversions and Cost / conv. from Columns. Cost / conv. is the platform’s CPA and Target CPA bidding uses the same definition. In the API it is metrics.cost_per_conversion, in micros.

Meta Ads Manager: Cost per result follows each ad set’s optimisation event, so it can mean cost per purchase in one row and cost per lead in the next. Add a fixed column such as Cost per purchase for like-for-like comparisons.

When the CPA ratio is undefined

With zero actions, cost per action is undefined, and a CPA of zero cannot estimate conversions from a budget. Reporting zero would misleadingly imply that outcomes were acquired at no cost.

Read the definition before comparing campaigns

Cost per acquisition (CPA): formula, examples and calculator explains what this number does and does not tell you, with the same caveats this calculator applies.

Questions, answered

How do you calculate CPA?

Divide ad spend by the number of counted actions for the same period and scope. 900 spent for 30 completed enquiries is a CPA of 30.00 per enquiry.

What is the CPA formula?

CPA = spend ÷ actions. Name the action (lead, purchase, new customer), because the same spend gives a very different CPA for each.

How do I work out the budget for a target CPA?

Multiply the target CPA by the number of conversions you want. 50 conversions at a 30.00 CPA need about 1,500 of spend.

How many conversions will my budget get?

Divide the budget by the expected CPA. A 600 budget at a 30.00 CPA buys about 20 conversions, if the CPA holds.

What is a good CPA?

One below your break-even CPA: the gross profit a conversion brings in before ad costs. There is no universal benchmark.

Is CPA the same as customer acquisition cost?

Only when the denominator is new customers. A cost per lead or per sign-up is a CPA, but not a customer acquisition cost.

Other free calculators