Cost Per Acquisition Calculator
Compute cost per acquisition, compare it against the break-even your margin dictates, and see why it is not the same number as customer acquisition cost.
Cost Per Acquisition Calculator
Results recalculate instantly on every keystroke. Nothing you type is transmitted.
What this result does not account for
- Media cost only — excludes salaries, tooling and overhead.
- Depends on your definition of a conversion.
- Blended across all campaigns unless segmented.
In short: CPA counts orders; CAC counts customers. 24,975 over 518 orders is 48.21 — but if only 62% are new buyers, the cost per new CUSTOMER is 77.76, a 29.55 gap that changes every conclusion.
Formula
CPA = spend ÷ conversions (orders)
CAC = spend ÷ NEW customers (always higher)
[('CPA', 'cost per ORDER, repeat purchases included'), ('CAC', 'cost per NEW CUSTOMER only'), ('break-even CPA', 'contribution per order'), ('the chain', 'CPA = CPC ÷ conversion rate')]
Worked Example
- Divide spend by conversions for cost per acquisition.
- Compute contribution per order — that is break-even.
- Compare the two to find profit per order.
- Apply the new-customer share to get true CAC.
- Compare CAC against lifetime value, never CPA.
24,975 over 518 conversions is 48.21 per acquisition. At a 128.00 order value and 42% contribution margin, break-even is 53.76, so each order contributes 5.55 after advertising — 2,872.68 in total, at 89.6843% of the ceiling. But only 62% of those orders came from new customers, so 321.16 customers were acquired at 77.76 each — 29.55 above the CPA. The chain confirms it: 1.35 ÷ 2.80% = 48.21.
Strengths & Limits Of This Model
Where this engine is strong
- Separates cost per order from cost per new customer
- Uses contribution margin for the break-even
- Derives CPA from the funnel chain as a cross-check
Where it stops
- Excludes loaded costs
- Definition-sensitive
Practical Use Cases
Judging a campaign
Comparing CPA against contribution per order.
Setting a target CPA
Working back from the margin you need.
Correcting an LTV:CAC ratio
Using CAC rather than CPA in the denominator.
Diagnosing the chain
Splitting CPA into click price and conversion rate.
Board reporting
Distinguishing media CPA from loaded CAC.
Methodology & Editorial Standards
Cost per acquisition is spend over conversions, counting every order. Customer acquisition cost applies the new-customer share to the same spend, and the page prints the gap because the two are routinely conflated in LTV ratios. Break-even is contribution per order after shipping, fees, discounts and returns rather than gross margin. The page stays deliberately inside the advertising account and states that a fully loaded customer acquisition cost adds salaries, tooling and overhead on top.
Computation runs in IEEE-754 double precision at full internal precision; rounding to two decimal places occurs strictly at the display layer, so no cumulative drift enters the result. All monetary outputs use accounting presentation — grouped thousands, two decimals, negatives in parentheses — so figures can be transcribed directly into a model or working paper. Division-by-zero and out-of-domain inputs return an em-dash rather than a misleading number.
This engine was reconciled against an independent reference implementation and hand-verified for the worked example above before release. Our full five-stage review process is published on the About Us page.
Disclaimer. This calculator is provided for informational and modelling purposes only and does not constitute financial, tax, legal, medical, or engineering advice. Verify all figures with a qualified professional before acting on them.
Cost Per Acquisition Calculator — 10 Expert FAQs
10 analyst-written answers to the questions practitioners actually ask — optimised for voice and answer-engine retrieval.
What is the difference between CPA and CAC?
CPA divides spend by conversions, so every order counts including repeat purchases. CAC divides spend by new customers only. Whenever existing customers buy, CAC is the larger figure, and the two answer genuinely different questions.
Which should I compare against lifetime value?
CAC, always. Lifetime value is a per-customer figure, so dividing it by a per-order cost inflates the ratio by exactly your repeat-purchase share. An LTV:CAC ratio computed against CPA is one of the most common errors in growth reporting.
What is a good cost per acquisition?
Anything below your contribution per order, which is the only benchmark that means anything. Industry averages are useless here because a business with a 70 per cent margin can profitably pay several times what a 20 per cent margin business can.
Should CAC include salaries and tools?
For board reporting, yes — a fully loaded CAC includes marketing salaries, software, agency fees and overhead, and it is frequently half as large again as the media-only figure. For campaign decisions the media-only version is the right one. Never compare the two against each other.
How do I lower cost per acquisition?
There are exactly two levers, because CPA equals cost per click divided by conversion rate. Pay less per visit through better targeting and quality signals, or convert more of the visits you already buy. Conversion work is usually the cheaper of the two.
Can a high CPA still be profitable?
Yes, if contribution per order is higher still, or if repeat purchases mean the first order is not the whole relationship. Subscription and consumable businesses routinely accept a first-order loss because the second and third orders carry no acquisition cost at all.
What counts as a conversion?
Whatever you define, which is why the metric needs care. Counting newsletter sign-ups alongside purchases produces a flattering CPA that cannot be compared against contribution per order. Keep the headline figure to the action that generates revenue.
Why does my CPA rise as I scale?
Because incremental audiences are less qualified and incremental auctions are more competitive. A rising CPA with spend is normal, and the question that matters is whether the MARGINAL acquisition is still below break-even, not whether the average is.
Does CPA include the cost of returns?
Not directly, but it should be reflected in your break-even. Contribution margin has to be net of expected returns, otherwise you are comparing acquisition cost against revenue you will refund. In high-return categories this changes the answer substantially.
Is target CPA bidding the same as this?
The platform's target CPA is a bidding instruction, not an economic limit. Set it below the break-even computed here so there is room for measurement error and for fixed costs. Setting it at break-even guarantees you contribute nothing.