Free tool

CPA calculator

Work out your cost per acquisition or cost per lead, how many conversions a budget should deliver, or the spend you need to reach a target. Enter any two of ad spend, conversions, and CPA.

Solve for

Ad spend

Total budget or amount spent

Conversions

Leads, sign-ups, demos, or customers

Count one stage consistently. Leads in, cost per lead out; customers in, cost per customer out. Mixing stages is what makes CPA figures disagree.

CPA

$125.00

$5,000.00 ÷ 40 conversions = $125.00 each

Conversions per $1,000: 8
Budget for 100 conversions: $12,500.00

The CPA formula

One formula for CPA, CPL, and cost per conversion.

Cost per acquisition is ad spend divided by the conversions it produced. Define the conversion as a lead and the same formula gives you cost per lead; define it as a paying customer and it gives you cost per customer.

Solve for CPA

CPA = Ad spend ÷ Conversions

The average cost of one lead, sign-up, demo, or customer.

Solve for conversions

Conversions = Ad spend ÷ CPA

How many conversions a budget should deliver at a known CPA.

Solve for ad spend

Ad spend = Conversions × CPA

What a conversion target will cost at the CPA you expect.

CPA can also be reached from the click side: CPA = CPC ÷ conversion rate. A $2.50 CPC at a 2% conversion rate is a $125 CPA, which is why a small landing page improvement moves CPA more than most bid changes.

Worked examples

What the numbers look like in practice.

Each row holds two of the values fixed and solves for the third (shown in bold). Paste any of them into the calculator above to check the arithmetic.

Scenario	Ad spend	Conversions	CPA
$5,000 spent for 40 demo requests	$5,000	40	$125.00
A $20,000 budget at a $250 target CPA	$20,000	80	$250.00
Booking 150 leads at $60 each	$9,000	150	$60.00
$12,000 spent for 8 closed customers	$12,000	8	$1,500.00

Beyond the number

What CPA tells you, and what it doesn't.

Cost per lead and cost per customer are different numbers

A $60 cost per lead with a 10% lead-to-customer rate is a $600 cost per customer. Both are CPAs; they just count different stages. Decide which stage actually pays the bills and measure that one, or you will optimize for cheap leads that never close.

Platform CPA is platform-reported

Each ad platform counts the conversions it claims credit for, and those claims overlap. Add up the CPAs from every platform and you will undercount the real blended cost. Blended CPA is total spend divided by the conversions your CRM or billing system actually recorded.

A good CPA depends on what a customer is worth

CPA only means something next to lifetime value. Use the LTV calculatorfor the other side of the ratio, and Cometly's attribution to measure CPA on the conversions in your CRM rather than the ones the platforms claim.

Want the CPA down without cutting spend? See how teams use Cometly to reduce CAC.

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FAQ

Cost per acquisition questions, answered.

CPA, CPL, and CAC, how they differ, and why platform-reported CPA rarely matches your CRM.

Talk to sales

What is CPA in marketing?

CPA is cost per acquisition: the average amount of ad spend it took to produce one conversion. The conversion can be a lead, a sign-up, a demo request, or a paying customer, so always say which one a CPA refers to.

How do you calculate cost per acquisition?

Divide total ad spend by the number of conversions. CPA = ad spend ÷ conversions. If you spent $5,000 and got 40 demo requests, the CPA is 5,000 ÷ 40 = $125 per demo.

How do you calculate cost per lead?

The same way, with leads as the conversion. Cost per lead = ad spend ÷ leads. $9,000 of spend that produced 150 leads is a $60 cost per lead. If you know your cost per click and conversion rate instead, CPL = CPC ÷ conversion rate.

What is the difference between CPA and CAC?

CPA usually measures a single campaign or channel against a single conversion type, and it usually counts only ad spend. CAC, customer acquisition cost, measures the full cost of acquiring a paying customer, typically including salaries, tools, and agency fees across all channels. CPA is a campaign metric; CAC is a business metric.

What is a good CPA?

One that leaves room for profit after the customer pays. That depends on your average order value or subscription price, your margin, and how many of your conversions become paying customers. A $125 cost per demo is cheap if a quarter of demos close into $10,000 deals and expensive if one in fifty closes into a $500 deal. Compare CPA with lifetime value rather than with industry averages.

How do I lower my CPA?

CPA is cost per click divided by conversion rate, so there are only two levers. Lower the cost per click by tightening targeting, improving ad relevance, and cutting placements and keywords that attract clicks but not conversions. Raise the conversion rate by matching the landing page to the ad, shortening forms, and sending the platform better conversion data so its bidding optimizes for the conversions that close.

Why is my platform CPA different from the CPA in my CRM?

Ad platforms count the conversions their own tracking attributes to their ads, using their own attribution windows, and several platforms often claim the same conversion. Your CRM records each lead or deal once. Blended CPA from the CRM is the honest number; platform CPAs are useful for comparing campaigns inside one platform.

Does this CPA calculator work for Google Ads, Meta, LinkedIn, and TikTok?

Yes. Spend divided by conversions is the same on every platform and in every currency. For a blended CPA across platforms, add up the spend from all of them and divide by the total conversions recorded in your CRM or billing system.

Leads are a cost.
Pipeline is the result.

Cometly connects ad spend to the leads, opportunities, and revenue in your CRM, so CPA is measured on outcomes that matter rather than platform claims.

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