ConversionMath

CPA Calculator

Calculate cost per acquisition to measure what you're really paying for each customer, signup, or conversion — and reverse it to plan budget and volume.

Your CPA

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Formula CPA = Spend ÷ Acquisitions

How to use this calculator

Enter your total ad spend and the number of acquisitions (conversions, purchases, signups — whatever your CPA is measuring). The calculator returns your cost per acquisition. Use the "Calculate" selector to solve instead for total spend or acquisition volume.

What is CPA?

Cost per acquisition (CPA) is the average cost to generate one conversion — typically a customer, purchase, signup, or other bottom-funnel outcome. CPA is one of the most important metrics in performance marketing because it directly measures the efficiency of your ad spend at producing real business outcomes. Unlike CPL (leads) or CPC (clicks), CPA tells you what you're actually paying for each unit of value.

When to use this calculator

  • Measuring ROAS and profitability on performance campaigns
  • Comparing cost efficiency across Google, Meta, TikTok, and other channels
  • Setting target CPA based on customer lifetime value and margin
  • Deciding whether to scale, maintain, or pause a campaign
  • Benchmarking against industry or historical performance

Frequently asked questions

What is a good CPA?
There's no universal benchmark. Your target CPA should be derived from your customer lifetime value (LTV) and gross margin — generally you want CPA to be a fraction of LTV (a common heuristic is CPA ≤ 1/3 of first-year gross profit, but it depends on your model). Industry averages are often misleading because margins and LTV differ so much.

How is CPA calculated?
CPA = Total Ad Spend ÷ Number of Acquisitions. If you spent $5,000 and got 100 purchases, your CPA is $50.

What's the difference between CPA and CAC?
They're related but not identical. CPA usually refers to the cost of a single conversion event (purchase, signup) within an ad platform. CAC (customer acquisition cost) is a broader business metric that includes all sales and marketing costs — not just ad spend — divided by new customers. CPA is a subset of what drives CAC.

CPA vs CPL — what's the difference?
CPL measures cost per lead (a prospect who has expressed interest). CPA measures cost per acquisition (a completed conversion, often a paying customer). CPA is usually significantly higher than CPL because only a portion of leads convert.

How do I lower my CPA?
Improve landing page and checkout conversion rate, tighten targeting, refine creative, eliminate underperforming campaigns, improve product-market fit or offer, and use smart bidding strategies that optimize toward CPA directly (like Google's Target CPA or Meta's cost cap bidding).

Can I set a target CPA in ad platforms?
Yes. Google Ads offers Target CPA (tCPA) bidding, and Meta offers cost cap and bid cap strategies. These work best when you have sufficient conversion volume — usually 30+ conversions in the past 30 days per campaign.

Is CPA the same as cost per sale?
Only if "acquisition" means a sale in your context. CPA is flexible — it can mean purchase, subscription signup, trial, account creation, or anything you define as the target conversion. The important thing is consistent definition across reporting.

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