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Marginory

CPA Calculator (Cost Per Acquisition)

Calculate CPA, break-even CPA, ROAS, and true profit per order including ad spend. Works for Facebook Ads, Google Ads, TikTok Ads, and any paid channel.

By Content reviewed

Campaign Metrics

$
%
$

Per-order Costs

$
$

Campaign Results

Conversions / orders20.0
Cost per click (CPC)$0.50
Cost per acquisition (CPA)$25.00
ROAS1.20x
Total revenue$600.00

Profitability

Break-even CPA$17.00
Profit per order (incl. CPA)-$8.00
Total campaign profit-$160.00
Profit margin (incl. ad cost)-26.7%

Worked example: CPA against contribution

$50 average order with a 40% contribution margin before ads ($20). Monthly ad spend $1,500.

CPA $12CPA $20CPA $28
Orders from ads1257554
Profit from ads$1,000$0$-428.57

Break-even CPA equals contribution per order — $20 here. Above it, more spend means more loss.

How this is calculated

Conversions: Clicks × Conversion rate
CPA: Ad spend / Conversions
CPC: Ad spend / Clicks
ROAS: Revenue / Ad spend
Break-even CPA: Average order value − Product cost − Other costs
Profit per order: AOV − Product cost − Other costs − CPA

Assumptions

  • Conversion rate: % of clicks that result in an order
  • Other costs includes platform fees + shipping per order
  • Break-even CPA: CPA at which profit = 0 (no other costs considered beyond product + other costs)

Using CPA for a Shopify store

Include actual payment/gateway fees, packing and seller-paid shipping in other per-order costs. A hypothetical $50 order with $30 product cost and $6 other costs has $14 available for acquisition before fixed overhead. At $200 ad spend, 1,000 sessions and 2% conversion, the model estimates 20 orders, $10 CPA and $80 campaign contribution. At 3% conversion with everything else unchanged, CPA falls to $6.67; this scenario assumes the extra orders have the same value and costs.

Increasing AOV raises the affordable acquisition budget only if contribution also rises; it does not lower measured CPA by itself. Set a target below break-even using your own overhead and profit requirement. With zero conversions, CPA is undefined and the spent advertising budget remains a loss.

Model a conversion-rate change, check payment costs or include subscriptions and overhead.

Review the market, fee bases and exclusions shown with this tool. Published rates and illustrative cost inputs have different certainty. Compare your breakdown with an actual order statement. Sources and methodology.

Related Tools

ROAS CalculatorProfit CalculatorBreak-Even CalculatorPricing Calculator

Frequently Asked Questions

What is CPA and how do I calculate it?
CPA (Cost Per Acquisition) = Ad spend / Conversions, where Conversions = Clicks × Conversion rate. Spend $200 with 1,000 clicks at a 4% conversion rate: conversions = 40, CPA = $200 / 40 = $5. That's what you pay in ad spend for each customer acquired, separate from product cost or fees.
How do I find my maximum affordable CPA (break-even CPA)?
Break-even CPA = Average order value − Product cost − Other costs (fees + shipping). A $40 AOV with $12 product cost and $6 in fees/shipping leaves $22 — that's the most you can spend acquiring a customer and still break even. Reserve your required profit and overhead allowance before setting an acquisition budget.
How is CPA different from ROAS and CPC?
CPC (cost per click) measures traffic cost only. CPA measures the cost of an actual sale — CPC divided by conversion rate. ROAS (Revenue / Ad spend) measures the inverse relationship: how much revenue each ad dollar returns. A campaign can show a great ROAS while still having a CPA above your break-even line if AOV is high but margin is thin — always check both metrics together, not just one.
What's a common mistake sellers make with CPA targets?
Using one CPA target across every product. A $15 item and a $150 item can have very different break-even CPAs even at the same margin percentage, because fixed per-order costs (like a $0.30 payment fee) are a much smaller share of the higher-priced order. Calculate break-even CPA per product or price tier, not storewide.
How do I lower my CPA without cutting ad spend?
Three levers move CPA without touching your budget: improving conversion rate (more buyers from the same clicks), improving order contribution (which raises the affordable CPA without lowering measured acquisition cost), and tighter audience targeting (higher-intent clicks convert more often). Raising conversion rate from 2% to 3% alone cuts effective CPA by roughly a third.
Does this calculator work for any ad platform?
Yes. Enter clicks, conversion rate and ad spend for the same campaign and period. Compare CPA with your own contribution before advertising, rather than an unsupported channel average. The calculator estimates orders from clicks and conversion rate; it does not connect to an ad account.