CAC, with its boundary visible.

CAC boundary calculator

Calculate assigned CAC and, when you can name a counterfactual, incremental CAC. Add contribution margin for payback and an optional forecast value for the matched LTV ratios.

Scope. This is a boundary calculator, not a causal test, industry benchmark or profitability verdict. The inputs are illustrative until you define their source, cohort and decision use.

1.Declare the object

Customer event What enters the denominator?

Acquisition window Which cost period is paired with the cohort?

Cost boundary What is included in the numerator?

2.Enter the numbers

Declared acquisition cost Use one currency or cost unit throughout.

New customers in cohort The denominator for assigned CAC.

Customers in the counterfactual Customers estimated to arrive without the intervention.

Incremental cost caused by intervention Required for an incremental CAC result.

Monthly contribution margin per customer Required for a payback estimate.

Forecast customer value / LTV (optional) Use the same cohort and contribution boundary.

Sample cohort Clear inputs Showing the calculator’s own sample cohort

Result

The result updates locally as you type.

Customer event

First paid contract

Acquisition window

1 to 31 July 2026

Cost boundary

Media, sales SDR allocation & onboarding

Assigned CAC

300

cost units per customer

declared cost / new customers

Incremental CAC

300

cost units per customer

incremental cost / additional customers

Assigned CAC payback

2.5

months

CAC / monthly contribution margin

Incremental CAC payback

2.5

months

CAC / monthly contribution margin

LTV:CAC

5

:1

forecast value / assigned CAC

CAC:LTV

0.2

:1

assigned CAC / forecast value

Cash calendarCash position per customer, month by month

Assigned CAC goes out in month 0; every month after returns the contribution margin. The bars cross zero at payback.

Undiscounted, with a constant monthly contribution and no churn: the assumptions inside the payback formula.

Source: your inputs.

Export

The result leaves as an exhibit: the declared boundary, the figures and the cash calendar, set on paper with the night band every figure on this site carries.

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isoglu-cac-boundary-analysis.png · .svg

Exhibit

CAC boundary analysis

Sinan Isogluisoglu.com/tools/cac/isoglu-cac-boundary-analysis.png

Enterprise valuation

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What this instrument is built on

The operating definition comes from the essay “What is CAC?”, the first of the routes below. The surrounding boundaries rest on four sources. All four are held in full text.

1. Gupta, Lehmann and Stuart (2004): customer value and its retention, margin, acquisition and discounting assumptions.

   10.1509/jmkr.41.1.7.25084 Full text held

2. Rust, Lemon and Zeithaml (2004): customer equity relative to incremental expenditure.

   10.1509/jmkg.68.1.109.24030 Full text held

3. Mulhern (1999): explicit inputs and profit concentration across customers.

   10.1002/(SICI)1520-6653(199924)13:1<25::AID-DIR3>3.0.CO;2-L Full text held

4. Malthouse and Blattberg (2005): forecast horizon and misclassification risk around customer value.

   10.1002/dir.20027 Full text held