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eBay Customer Acquisition Cost Estimator

The eBay Customer Acquisition Cost Estimator calculates how much marketing spend is required, on average, to produce one new customer. It can separate new customers from total orders and optionally subtract directly attributable campaign credits or rebates from gross spend.

This metric is useful for promoted listings, off-platform ads, influencer campaigns, and other acquisition programs. Compare the result with contribution profit from a first order and with estimated customer lifetime value. A low acquisition cost is not automatically profitable if repeat purchasing is weak or order margins are thin.

Calculator inputs

$
$
orders
%
$
$
Result
—
Customer acquisition cost
Estimated new customers—
Net acquisition spend—
Cost per attributed order—
First-order contribution after CAC—
First orders needed to cover spend—
CAC as share of first-order profit—

1. Define the campaign period
Use matching dates for spend, attributed orders, and customer status.

2. Enter gross spend and credits
Include advertising, creative, agency, and other directly attributable acquisition costs; subtract only confirmed credits.

3. Record attributed orders
Use the attribution method applied consistently in your reporting.

4. Estimate the new-customer share
Enter the percentage of attributed orders placed by first-time buyers.

5. Compare CAC with contribution profit
A first order may not recover CAC; assess repeat purchases with the customer lifetime value estimator.

Estimated new customers = Attributed orders × New-customer rate ÷ 100
Net acquisition spend = Advertising spend + Other acquisition cost − Credits
Customer acquisition cost = Net acquisition spend ÷ Estimated new customers

Where:

  • Attributed orders: orders credited to the campaign
  • New-customer rate: share of attributed orders from first-time buyers
  • Contribution profit: revenue remaining after variable order costs, before acquisition spend

Assumptions: Each estimated new customer is represented by one attributed order during the measured period.

What the result means

CAC is the average net acquisition spend per estimated new customer in the selected period.

Attribution rules and customer identification quality can materially change the result.

Given:

  • Advertising spend: $1,200
  • Other acquisition cost: $200
  • Campaign credits: $0
  • Attributed orders: 90
  • New-customer share: 70%
  • First-order contribution profit: $18

Calculation:
Estimated new customers = 90 × 70% = 63. Net acquisition spend = 1,200 + 200 = $1,400. CAC = 1,400 ÷ 63 = $22.22. First-order contribution after CAC = 18 − 22.22 = −$4.22.

Result:
$22.22 estimated CAC.

Interpretation:
The first order does not fully recover acquisition cost, so profitability depends on repeat contribution or lower campaign spend.

Should seller fees be included in CAC?

Usually seller fees belong in order contribution profit rather than acquisition spend. The important point is to avoid counting the same cost twice.

What if one new customer places multiple campaign orders?

Use unique new customers when available. The rate-based estimate can overstate customer count when repeat orders occur within the campaign window.

Can I use clicks instead of orders?

Not for customer acquisition cost. Click-based metrics measure traffic efficiency, while CAC requires acquired customers.

How should organic customers be treated?

Exclude customers not reasonably attributed to the measured campaign. Mixing organic and paid acquisition can make CAC look artificially low.

What should CAC be compared with?

Compare it with first-order contribution profit, payback period, and customer lifetime value using the same margin definition and time horizon.