CPA Calculator: Cost Per Acquisition
Measure how much you spend for each conversion (lead, signup, or purchase) in a campaign or channel.
CPA (Cost Per Acquisition) is ad spend per conversion. Formula: CPA = Ad Spend ÷ Conversions. Example: $10,000 ÷ 200 = $50 CPA. Unlike CAC, CPA is usually campaign-level media only.
Total amount spent on the campaign or channel
Number of desired actions (purchases, sign-ups, leads)
Cost per Acquisition (CPA)
$50.00
How it works
Cost Per Acquisition (CPA) is a campaign-level metric: ad spend divided by conversions. Unlike CAC, CPA usually excludes salaries and overhead and is scoped to one campaign or channel. Use it for day-to-day media optimization; use CAC for fully loaded unit economics.
How to use this calculator
Follow these steps to get an accurate CPA Calculator result.
- Open the CPA Calculator and select your currency if needed.
- Enter Total Ad Spend: the total amount spent on the campaign, ad group, or channel you want to evaluate.
- Enter Conversions: the number of desired actions (purchases, sign-ups, form submissions) from that same campaign and time period.
- Your CPA appears instantly. Compare it to your average order value or customer LTV to judge whether the campaign is profitable.
Worked examples
Plug in sample numbers to see how the CPA Calculator formula works in practice.
Lead gen campaign
- Ad spend
- $10,000
- Conversions
- 200
CPA = $10,000 ÷ 200 = $50
Benchmarks
Directional ranges—always prefer your own baselines and unit economics.
| Context | Guidance |
|---|---|
| Good CPA | Below the contribution value of the conversion |
| Ecommerce | Compare to margin per order |
| SaaS trials | Compare to LTV × trial-to-paid rate |
| vs CAC | CAC is almost always higher than media CPA |
Common mistakes
- Mixing conversion definitions — Be explicit: lead vs trial vs paid customer.
- Calling CPA “CAC” in board decks — Investors expect fully loaded CAC for unit economics.
Frequently Asked Questions
What is CPA?
CPA stands for Cost Per Acquisition (sometimes Cost Per Action): the average ad spend required to generate one conversion, such as a lead, trial, or purchase within a campaign.
How do you calculate CPA?
CPA = Total Ad Spend ÷ Number of Conversions. Example: $10,000 spend and 200 conversions = $50 CPA. Keep spend and conversions on the same campaign and time window.
What is the difference between CPA and CAC?
CPA is campaign-level and usually includes only media spend. CAC is business-level and includes sales and marketing overhead. CAC is typically much higher than CPA. See our CAC vs CPA comparison for details.
What is a good CPA?
A good CPA is below the contribution value of the conversion. For ecommerce, compare to margin per order; for SaaS, compare to LTV and conversion-to-paid rates. There is no universal target.
Is there a free CPA calculator?
Yes. This CPA calculator is free with no signup. Enter spend and conversions for an instant result, then compare with our CAC and ROAS tools.
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