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CPA formula and cost per acquisition calculator
The CPA formula is simple: cost per acquisition equals what you spent divided by the conversions it bought. Convertica's free calculator does the sum and shows how cost per click and conversion rate combine into CPA, and the break-even calculator shows the most a conversion can cost before it loses money. Both work in any currency.
Short answer
The CPA formula is total cost divided by the number of conversions. Cost per acquisition tells you what you paid, on average, for each sale, lead or sign-up a campaign produced. It also equals cost per click divided by conversion rate. A CPA below break-even, the value of a conversion times gross margin, makes money on the first sale.
- Name the conversion you count in every report, because a cost per lead and a cost per sale are very different numbers.
- Say whether you report paid media CPA or fully loaded CPA, and never compare one with the other.
- CPC, CPL, CPA and CAC all divide a cost by a count; what changes is what is counted.
- At the same cost per click, a higher conversion rate lowers CPA, so a poor CPA can start on the landing page rather than in the ads.
- There is no universal good CPA, because it depends on what a conversion is worth to you.
Cost per acquisition calculator
Free to use, no sign-up. Any currency. The result updates as you type.
Cost per acquisition (CPA)
62.50
5,000 cost ÷ 80 conversions = 62.50 per conversion.
Cost per click: 5,000 ÷ 2,000 clicks = 2.50. Conversion rate: 80 ÷ 2,000 = 4.00%.
Check: CPA = cost per click ÷ conversion rate = 2.50 ÷ 4.00% = 62.50.
At the same cost per click, a conversion rate a quarter higher (5.00%) would bring CPA down to 50.00.
Formula
CPA = total cost / conversions
= cost per click / conversion rateBreak-even CPA calculator
The most one conversion can cost before it loses money on the first sale.
Break-even CPA
60.00
150 value per conversion × 40% gross margin = 60.00. A conversion that costs more than this loses money on its first sale.
Your CPA of 62.50 is above break-even: each conversion loses about 2.50 on its first sale, unless repeat purchases make it back.
Formula
break-even CPA = value per conversion * gross marginWhat is the CPA formula?
The CPA formula is total cost divided by the number of conversions. Cost per acquisition tells you what you paid, on average, for each sale, lead or sign-up a campaign produced. With 5,000 spent and 80 conversions, CPA is 5,000 / 80 = 62.50. Lower is better, as long as conversion quality holds.
CPA = total cost / conversionsCPA is also written as cost per action, especially in ad platforms: Google Ads calls its CPA bid strategy "Target CPA (cost-per-action)". The formula does not change; what changes is the action you count. Name it in every report, because a cost per lead and a cost per sale are very different numbers.
How to use the CPA calculator
- Pick one conversion. A purchase, a lead form, a booked call or a trial sign-up. Not a mix.
- Enter total cost. Ad spend for the campaigns and dates you are measuring, plus fees if you want a fully loaded CPA.
- Enter conversions. How many of that conversion the same campaigns produced over the same dates.
- Add clicks if you have them. The result then shows cost per click and conversion rate, the two parts that make up CPA.
- Check break-even. Enter the value of a conversion and your gross margin in the second calculator to see the most you can afford.
How to calculate CPA: a worked example
To calculate CPA, total the cost of a campaign over a period, count the conversions it produced in the same period, and divide. Then compare the result with your break-even CPA to see whether those conversions made money. The numbers below are the default values in the calculators, made up to show the arithmetic; they are not a benchmark.
- Cost: 5,000. Clicks: 2,000. Conversions (sales): 80.
- CPA = 5,000 / 80 = 62.50.
- Cost per click = 5,000 / 2,000 = 2.50. Conversion rate = 80 / 2,000 = 4.00%.
- Check: 2.50 / 0.04 = 62.50, the same CPA from its two parts.
- Average order value 150 at a 40% gross margin gives a break-even CPA of 150 × 0.40 = 60.00.
- The campaign's CPA is 2.50 above break-even, so each first sale loses 2.50. At a 2.50 cost per click, the conversion rate needed to break even is 2.50 / 60.00 = 4.17%.
That last step is the useful one. The ads are not far off: the landing page needs to convert 4.17% of clicks instead of 4.00% for this campaign to pay for itself. The free landing page analyzer is a quick way to see what is holding the page back.
What costs go into CPA?
CPA can include ad spend only, or every cost of winning the conversion: agency or freelancer fees, software, creative production and discounts given to close the sale. Neither is wrong. Paid media CPA compares campaigns; fully loaded CPA tells you what acquisition really costs. Say which one you report, and never compare one with the other.
| Version | Cost included | Worked example | Use it for |
|---|---|---|---|
| Paid media CPA | Ad spend only | 5,000 / 80 = 62.50 | Comparing campaigns, ad groups and channels; bid targets |
| Fully loaded CPA | Ad spend plus fees, tools and creative | (5,000 + 1,500) / 80 = 81.25 | Budgeting and checking that acquisition is profitable |
| Blended CPA | All marketing cost, paid and unpaid channels | Total marketing cost / all conversions | The business view, without trusting one platform's attribution |
You may also see eCPA (effective cost per acquisition). It is the same formula applied to campaigns bought on another basis, such as cost per click or per thousand impressions, so they can be compared with campaigns bought on a CPA basis.
CPA vs CAC, CPL and CPC
CPA, CAC, CPL and CPC all divide a cost by a count; the difference is what is counted. CPC divides by clicks, CPL by leads, CPA by any conversion you choose, and CAC by new paying customers using all sales and marketing costs. Each step down the funnel counts fewer people, so the cost per person rises.
| Metric | Formula | Typical scope |
|---|---|---|
| CPC (cost per click) | Ad cost / clicks | Keyword, ad or campaign |
| CPL (cost per lead) | Ad cost / leads | Lead generation campaigns |
| CPA (cost per acquisition or action) | Cost / conversions | Campaign or channel, for the conversion you choose |
| CAC (customer acquisition cost) | All sales and marketing cost / new paying customers | The whole business, over a month or quarter |
From cost per lead to cost per customer
For lead generation, the CPA you see in the ad account is usually a cost per lead. Follow it through to sales before you judge it. With 5,000 spent and 200 leads, CPL is 5,000 / 200 = 25.00. If 10% of leads become customers, those 200 leads produce 20 won deals, and the cost per customer is 5,000 / 20 = 250.00.
The break-even cost per lead works the same way as break-even CPA. A lead is worth the average deal value times the close rate: 2,000 × 0.10 = 200. At a 50% gross margin, a lead can cost up to 200 × 0.50 = 100.00 before it loses money.
How does conversion rate affect CPA?
Conversion rate sets CPA directly: CPA equals cost per click divided by conversion rate. At the same cost per click and spend, a conversion rate 25.0% higher cuts CPA by 20.0%. That is why a campaign with sound targeting can still have a poor CPA: the problem is often on the landing page, after the click.
CPA = cost per click / conversion rateThe default example at a fixed 2.50 cost per click and 2,000 clicks, against the 60.00 break-even CPA:
| Conversion rate | Conversions from 2,000 clicks | CPA | Against break-even (60.00) |
|---|---|---|---|
| 2.00% | 40 | 125.00 | 65.00 above |
| 3.00% | 60 | 83.33 | 23.33 above |
| 4.00% (current) | 80 | 62.50 | 2.50 above |
| 5.00% | 100 | 50.00 | 10.00 below |
| 6.00% | 120 | 41.67 | 18.33 below |
Moving from 4.00% to 5.00% takes CPA from 62.50 to 50.00, and turns a loss of 2.50 per first sale into 10.00 of gross profit, without touching a bid. Google's own help center notes that your actual CPA depends on things outside its control, including changes to your website and your real conversion rate.
To find your rate, use the conversion rate calculator. To find what is holding it down, Convertica's free CRO audit checks the page your ads send people to: the first screen, calls to action, forms, trust, mobile, speed and AI agent readiness, ranked by likely impact.
What is a good CPA?
A good CPA is one below your break-even CPA: the value of a conversion multiplied by your gross margin. Anything under that line makes money on the first sale; anything over it loses money unless the customer comes back. There is no universal good CPA, because it depends entirely on what a conversion is worth to you.
That is why this page publishes no average CPA by industry. A figure averaged across businesses with different prices, margins and definitions of a conversion cannot tell you what your own campaign can afford. Your break-even CPA can.
First sale or lifetime value?
Break-even CPA on the first order is the safe line. If customers reliably buy again, you can afford more, up to the gross profit a customer brings in over the period you are prepared to wait for it. Use real repeat purchase data from your own store, not a hoped-for figure, and remember that money returned in a year is worth less than money returned this month.
What is target CPA in Google Ads?
Target CPA is a Google Ads automated bid strategy in which you set the average cost per conversion you want, and Google sets bids to get as many conversions as it can at that average. Some conversions will cost more than the target and some less. Set it at or below your break-even CPA, not at a figure from someone else's account.
- It is an average, not a cap. Google's help center says it tries to keep your cost per conversion equal to the target overall.
- It optimizes what you count. Bidding uses only the conversion actions included in the "Conversions" column, so include the actions that matter to the business and leave out the rest.
- Names are changing. Google says that from June 2026 "Maximize conversions with a Target CPA" is labeled "Target CPA", with the same bidding behavior.
When conversions have a revenue value, as in ecommerce, a ROAS target often fits better than a CPA target. See the ROAS meaning and ROAS calculator.
How to lower your cost per acquisition
To lower cost per acquisition, raise the conversion rate after the click, pay less for each click, or stop paying for clicks that never convert. Of the three, conversion rate is the lever most advertisers leave alone, although it is the one the ad platform cannot change for you.
- Match the landing page to the ad. The same offer, wording and product the ad promised, on the first screen, on a phone. More in the guide on how to optimize landing pages.
- Remove friction. Fewer form fields, guest checkout, clear prices and shipping costs before the last step.
- Add trust where the decision is made. Reviews, guarantees and contact details near the call to action.
- Cut wasted spend. Negative keywords, excluded placements and audiences, and paused ads whose CPA sits above break-even.
- Fix tracking first. Duplicate or missing conversions make CPA wrong in both directions.
- Test changes properly. Run landing page changes as A/B tests and read them with the statistical significance calculator, so a lower CPA is real and not noise.
Common CPA calculation mistakes
- Mixing conversion types. Leads and sales added together give a CPA that describes neither.
- Mismatched dates. Spend from one month divided by conversions that include another month's clicks.
- Mixing sources. Ad platform spend divided by conversions from a different analytics tool, which counts differently.
- Ignoring conversion quality. A cheaper lead that never buys costs more than a dearer one that does.
- Reading tiny numbers. With a handful of conversions, one more or less swings CPA a long way. Wait for more data before you act.
Related calculators
CPA is one of three numbers that explain most paid media results, alongside return on ad spend and conversion rate.
See all free tools and how they fit together.
CPA formula FAQ
What is the CPA formula?
The CPA formula is total cost divided by the number of conversions: CPA = cost / conversions. For example, 5,000 in ad spend that brings 80 sales is a CPA of 5,000 / 80 = 62.50. Take both numbers from the same campaigns and the same date range.
How do you calculate cost per acquisition?
Add up what a campaign cost over a period, count the conversions it produced in the same period, and divide the cost by the conversions. Decide first whether cost means ad spend only or also includes agency fees, tools and creative, and use the same definition every time.
What is the difference between CPA and CAC?
CPA is usually measured per campaign or channel and counts any conversion you choose, such as a sale, lead or sign-up, against the ad cost that bought it. CAC (customer acquisition cost) counts only new paying customers and divides all sales and marketing costs by them, so CAC is normally higher and broader.
What is a good CPA?
A good CPA is one below your break-even CPA, which is the value of a conversion multiplied by your gross margin. There is no universal good figure: it depends on what a conversion is worth to you. A product with a 150 order value and a 40% margin can afford up to 60 per first sale.
How do I calculate break-even CPA?
Multiply the value of one conversion by your gross margin. For a sale, use the average order value; for a lead, use the average deal value times the share of leads that become customers. For example, 150 × 40% = 60, so a sale that costs more than 60 to win loses money on its first order.
Is CPA cost per acquisition or cost per action?
Both. Advertisers use CPA for cost per acquisition, where the action is a sale or a new customer, and for cost per action, where it can be any tracked goal such as a lead, sign-up or app install. Google Ads uses cost per action. The formula is the same: cost divided by the number of those actions.
What is the difference between CPA and cost per lead?
Cost per lead (CPL) is CPA where the conversion is a lead, such as a form submission or call. It divides cost by leads, not by customers, so it is always lower than the cost of a customer. With 5,000 spent, 200 leads and 10% of leads becoming customers, CPL is 25.00 and the cost per customer is 250.00.
How does conversion rate affect CPA?
CPA equals cost per click divided by conversion rate, so at the same cost per click, a higher conversion rate lowers CPA in proportion. Going from a 4% to a 5% conversion rate at a cost per click of 2.50 cuts CPA from 62.50 to 50.00, a 20% drop, with no change to the ads.
How do I calculate CPA in Excel or Google Sheets?
Put cost in one cell and conversions in another, then divide: with cost in B2 and conversions in C2, enter =B2/C2. To avoid an error on rows with no conversions, use =IF(C2=0,"",B2/C2), and treat those rows as having no CPA yet rather than a CPA of zero.