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Methodology

Customer Acquisition Cost Planner methodology

Allocate shared acquisition cost across two aligned channels and compare loaded, blended and marginal CAC.
Duc Nguyen X.By Duc Nguyen X.· Founder, Margin101Last reviewed: View update historyMethodology

Educational only: Business decision support, not accounting, tax or legal advice.

Privacy: Calculations run locally; Margin101 does not receive your commercial inputs.

Update policy: Reviewed when formulas or official dependencies change.

Scope: Market-neutral small-business planning using your own assumptions.

1. Formulas and units

Total Acquisition Cost
totalAcquisitionCost = sum of channel loaded costs

Where

totalAcquisitionCost
Total Acquisition Cost (money)Source: Calculated output
Total Customers
totalCustomers = sum of acquired customers

Where

totalCustomers
Total Customers (units)Source: Calculated output
Blended CAC
blendedCac = total acquisition cost ÷ total customers

Where

totalAcquisitionCost
Total Acquisition Cost (money)Source: Calculated output
totalCustomers
Total Customers (units)Source: Calculated output
blendedCac
Blended CAC (money)Source: Calculated output
Marginal CAC
marginalCac = incremental spend ÷ incremental customers

Where

incrementalSpend
Incremental spend (currency units on one consistent basis)Source: Business record
incrementalCustomers
Incremental customers (whole or operational units)Source: Business record
totalCustomers
Total Customers (units)Source: Calculated output
marginalCac
Marginal CAC (money)Source: Calculated output
Attribution Window Mismatch
attributionWindowMismatch = channel attribution windows are unequal

Where

attributionWindowMismatch
Attribution Window Mismatch (boolean)Source: Calculated output

Money inputs and outputs use the currency selected in the scenario without changing the canonical methodology. Rates, margins, utilisation and buffers are entered as percentages and converted to decimal values for calculation.

2. Worked example

Input assumptions

Worked values below come from the same registered engine and visible default assumptions.

Calculation and outputs

Example

Worked values below come from the same registered engine and visible default assumptions.

Total Acquisition Cost
1,800.00 currency units
Total Customers
15
Blended CAC
120.00 currency units
Marginal CAC
150.00 currency units
Attribution Window Mismatch
Unreachable

The exact engine-derived outputs are shown in the labelled rows below.

Interpretation

Blended CAC combines direct and allocated shared acquisition costs, while marginal CAC keeps the incremental test visible.

3. Validation and boundary checks

  • Channel A and channel B retain stable IDs through calculation and display.
  • Each row reconciles direct spend + allocated shared cost = loaded cost.
  • Loaded channel CAC equals loaded cost ÷ acquired customers, with zero customers explicit.
  • Compared attribution windows remain visible and mismatches are flagged.

4. Assumptions and source classification

  • Channel A and channel B use one aligned currency and acquisition basis.
  • Shared acquisition cost is allocated only by the entered relative weights.
  • Attribution windows are user records; the planner flags but does not normalise a mismatch.
  • No provider rate, market benchmark, country rule or policy constant is embedded.

This planner has no current policy-data dependency. Its commercial assumptions are user supplied. Registered family-level regression suites exercise the shared business-logic engine and worked-result reconciliation.

5. Limitations

  • The workflow does not forecast demand, retention, conversion or campaign performance.
  • It does not replace financial, accounting, tax or legal advice.

This is educational decision support, not tax, accounting, legal or financial advice. Check the treatment of your actual transactions under the rules that apply to your business and seek qualified advice where appropriate.

6. Update and evidence policy

Registered family-level suites test formula invariants and example reconciliation; the release ledger records that coverage without claiming a separate oracle for every line of public copy. There is no official threshold or benchmark to refresh for this planner. Commercial inputs remain user-supplied because they vary by business and contract.

Change history

  1. : Initial public release of the planner and methodology after pre-launch calculation, content, source and interaction review.

Related reading

Guides to interpret the decision and its assumptions.

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