Example numbers. One campaign. Replace with yours.
Cost per acquisition
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…How to use the CPA calculator
This CPA calculator works out your cost per acquisition and checks it against what one acquisition is worth.
- Pick the tab you have numbers for.
- Enter ad spend and conversions from one report and date range, one kind of conversion (sales, or leads and trial sign-ups).
- Add value per acquisition (order value, or first-year value per customer if they reorder or renew) and contribution margin (after product, delivery, fees and returns, before ads; gross margin for SaaS).
- Open “+ Add” for clicks, a profit goal, a close rate and LTV, then share with Copy result or Copy link.
The CPA formula
To calculate cost per acquisition, divide ad spend by the conversions it brought in.
Formula
CPA = ad spend ÷ conversions
The A can be a sale, a sign-up or a lead. Count ad spend only; agency fees and salaries belong in CAC. The full CAC calculator adds them per new customer.
CPA calculation example
In a cost per acquisition calculation, $5,000 of ad spend for 100 conversions is a $50.00 CPA.
How to calculate cost per acquisition from CPC
CPA, also called cost per conversion, can start from your click price:
Formula
CPA = CPC ÷ conversion rate
$2.50 per click at 5% is $50.00 too. Type the rate as a percent in the CPA calculator.
What is a good cost per acquisition?
A good CPA is one below your break-even CPA, the most one acquisition can cost before it loses money. The same $50.00 CPA gets two verdicts: on a $200 sale at 40% margin, break-even is $80.00, a $30.00 profit; on a $100 sale it is $40.00, a $10.00 loss.
For context, WordStream by LocaliQ’s Google Ads Benchmarks 2026 put the median cost per lead at $66.69, $93.69 for Business Services (US search campaigns, April 2025 to March 2026). Compare your cost per lead with it, never your cost per customer.
Break-even CPA and target CPA
Your break-even CPA is the value of one acquisition times your contribution margin.
Formula
break-even CPA = value per acquisition × contribution margin
$200 × 40% = $80.00, your ceiling. The target takes your profit goal off the margin:
Formula
target CPA = value × (margin − profit goal)
$200 × (40% − 10%) = $60.00, the same target the break-even ROAS calculator gives, so a $50.00 CPA is $10.00 under. Type the target into Google Ads Target CPA bidding; it aims at an average, so some conversions cost more. If Google counts leads, not closed deals, type your per-customer target times your close rate (at 20%, a $250.00 customer target is $50.00 per lead).
Cost per lead vs cost per customer
In lead gen, what has to pay back is the cost per customer: cost per lead ÷ close rate, which the CPA calculator shows once you set a close rate. $5,000 for 100 leads is $50.00 per lead; at a 20% close rate, 20 customers cost $250.00 each. Against an $800.00 break-even on a $2,000 customer at 40% margin, that is $550.00 profit each. Use a customer’s value (not a lead’s), the close rate from the conversion you counted (request to customer, not held demo to customer) and a period old enough for leads to close.
CPA vs CAC, LTV and ROAS
| Metric | What it divides | Use it to |
|---|---|---|
| CPA | ad spend ÷ conversions | compare campaigns |
| CAC | all sales and marketing cost ÷ new customers | judge what a customer costs the business |
| LTV ÷ CPA | lifetime value ÷ ad cost per customer | see how many times a customer repays its ad cost |
| ROAS | revenue ÷ ad spend | run the same test as CPA, per order |
How to lower your CPA
The second cost per acquisition formula, CPC ÷ conversion rate, gives two levers: a lower click price and a higher conversion rate.
Close the gap the result shows. At $2.50 a click and 5%, a $100 sale at 40% margin loses $10.00 against a $40.00 break-even. A 6.25% conversion rate closes it, or a $2.00 CPC, the most you can pay per click at 5%.
Move budget to the lowest CPA per offer. Compare campaigns within one platform, on one conversion type.
Scale while you’re under break-even. The profit per acquisition is your room. Raise spend in steps and recheck: more spend can buy pricier clicks.
Frequently asked questions
What is the difference between CPA and CAC?
CAC is higher for the same customers, because it adds every non-ad cost of winning them. $5,000 of ads that wins 20 customers is $250.00 each in ad spend. Add an illustrative $3,000 of other sales and marketing cost, such as salaries and tools, and CAC is $400.00 each ($8,000 ÷ 20). To see it in the CPA calculator, type ad spend plus agency fees, tools and salaries as the spend, with new customers as the conversions or your close rate set: the result is your CAC. If CPA is under break-even but CAC isn’t, the ads pay but the whole program doesn’t yet, so set the target CPA low enough to leave room for those costs.
What is cost per acquisition?
Cost per acquisition is the average ad cost of one conversion. The A also reads as “action”: Google’s Target CPA bidding calls it cost-per-action. It is the same number, so this cost per acquisition calculator gives your cost per action too.
How to calculate CPA in Google Ads?
Read the Cost / conv. column: total cost ÷ conversions. It can differ a little from spend ÷ your own count, because it leaves out clicks that can’t be tracked for conversions, can include modeled conversions and books each conversion on the click’s date. A recent week’s CPA can still fall as late conversions arrive, so judge it once those clicks have had time to convert. Check what the column holds: it counts primary conversion actions, and by default most actions are included. Segment the All conversions column by conversion action, keep only bottom-of-funnel actions such as the purchase as primary, and match the count against your own orders or new leads before you type it into the CPA calculator; calls from existing customers are not new acquisitions.
What is a good LTV to CAC ratio?
Above 3, by David Skok’s guideline for SaaS businesses. It applies to LTV to CAC, with LTV before any margin adjustment and gross margins of 80% or more assumed, and Skok says it can sometimes be broken. The CPA calculator’s LTV ÷ CPA leaves non-ad costs out, so the same customer scores higher there, which is why the tool shows it as a plain number with no “good” line. Below about 80% margin, type LTV × margin instead: a $120 LTV is 4.0 times a $30.00 CPA, but at 35% margin ($42.00) only 1.4 times.
How much should my target CPA be?
Below your break-even, by your profit goal. For Target CPA bidding, Google suggests starting from your average CPA over the last 30 days, adjusted for conversion delays, and judging results over 30 days with at least 30 conversions. Start near your recent average and move it in steps toward your profit-goal target while results hold. On Meta, the target goes in the cost per result goal bid strategy, which targets an average, judged weekly, and isn’t guaranteed.
What is the difference between cost per acquisition and cost per lead?
Cost per lead is a CPA where the acquisition is a lead. At the $93.69 Business Services median cost per lead and an illustrative 20% close rate, each customer costs $468.45 in ads.
What is the difference between CPA and ROAS?
When one conversion is one order, they are the same test seen two ways. On a $200 order, a $50.00 CPA is a 4.0 ROAS (400%), and a 400% target ROAS means a $50.00 target CPA. For the full order cost stack, ROAS and ACoS, use the break-even ROAS calculator.
How do you calculate CPA on Meta?
Meta reports cost per result: amount spent ÷ results. That is a CPA only when the result is a purchase or a lead, so use cost per website purchase or cost per lead. Meta’s default attribution is 7-day click, 1-day view and 1-day engagement, so it can count a sale from someone who only saw the ad.
Should I add all channels together?
Add them for what a customer costs the business from ads, but divide total spend by your own count of orders or leads from paid traffic, not the sum of platform conversions: two platforms can both credit the same sale, so the sum double counts. Compare platforms on that one count, by source in your store or analytics, before moving budget. Use each platform’s own CPA to set its bidding target. Run the CPA calculator once per channel, then once on the totals.
Should I use first-order value or first-year value?
First-order value tells you whether the first order pays back; first-year value, whether the customer pays back within 12 months, with the ad cash spent up front. Run the CPA calculator with each value: on $3,000 for 100 new customers, a $30.00 CPA loses $13.20 each against a $16.80 break-even on a $48 order at 35% margin, but makes $12.00 each against $42.00 on $120 a year (2.5 orders). Count new-customer purchases only: repeat orders in the count would double count the reorders already in the value.