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NumLuma› Business›CPA
Business · calculator Business Profit & Pricing Calculators ↗

CPA Calculator

Calculate cost per acquisition from campaign spend and conversions. Compare acquisition efficiency with ROAS, CAC and conversion rate.

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Cost per acquisition Live result
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Calculation breakdown
How to read this result

The result is the average campaign spend per conversion under your conversion definition. Compare it with the value and profitability of that conversion before deciding whether the CPA is sustainable.

More actions
Useful next calculationConversion Rate
How to use it

A clear result in a few inputs.

  1. Enter the requested values.Use consistent units and the real values for your scenario.
  2. Read the main result and breakdown.NumLuma recalculates immediately when an input changes.
  3. Check the formula and assumptions.Use the supporting context before making a real-world decision.

What this calculator does

CPA divides campaign spend by the number of conversions attributed to that campaign. The metric is only as meaningful as the conversion definition: a purchase, qualified lead, signup and app install can all produce very different CPA values.

What to know before you use the result

  • Define what counts as a conversion before comparing CPA across campaigns.
  • Use spend and conversions from the same attribution window and reporting period.
  • CPA is a campaign metric; customer acquisition cost can include a broader set of sales and marketing expenses.

Common mistakes to avoid

  • Comparing purchase CPA with lead CPA as though they represent the same outcome.
  • Using conversions from a wider time range than the spend data.
  • Assuming a low CPA is profitable without considering order value or margin.

Where this calculation is useful

Lead generationEcommerce acquisitionApp installsCampaign optimization

Related concepts

cost per acquisitioncost per conversioncampaign efficiencyattribution
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  • No sign-up required
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  • Inputs processed locally
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Assumptions & scope

Know what the number includes.

Commercial business intent. Define the metric precisely and distinguish it from neighboring metrics to avoid thin or interchangeable pages.

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Business Profit & Pricing Calculators

Best for pricing decisions, campaign analysis and operating-metric checks.

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Learn the concept

CPC, CPM, CTR and CPA: How Ad Metrics Work Together

Understand CPC, CPM, CTR and CPA, what each metric measures, and why no single advertising metric tells the whole story.

Read guide →
Quick answers

About the cpa calculation.

How is CPA calculated?

CPA equals campaign spend divided by the number of attributed conversions.

What counts as an acquisition?

That depends on the goal you define, such as a sale, lead, signup or install. Keep the definition consistent when comparing results.

How is CPA different from CAC?

CPA is commonly tied to a campaign conversion, while CAC often includes broader customer-acquisition costs across marketing and sales.