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Allowable CAC calculator

First-order allowable CAC is retained first-order revenue minus non-acquisition variable costs and the contribution the business needs to keep. Subtract other acquisition costs from that total ceiling to find the remaining media-only allowance.

By GaaS editorial · Sources checked September 7, 2026 · No signup required

Enter your numbers

Illustrative values are loaded. Replace them with your own numbers. Each field explains its units and accepted precision.

Currency

Sets the labels only. Enter all amounts in one currency; no exchange conversion is applied.

Retained first-order revenue

Average retained revenue from a new customer's first order. Exclude pass-through taxes and account for refunds consistently. Money amount, up to 2 decimal places.

Non-acquisition variable costs

Costs of serving that first order. Keep sales, media, and other acquisition costs out of this field. Money amount, up to 2 decimal places.

Contribution to retain

Amount per new customer to keep after all acquisition costs. Enter your own overhead and operating reserve. Money amount, up to 2 decimal places.

Other acquisition costs per customer

Included sales, creative, agency, and software acquisition costs allocated per new customer, excluding media. Money amount, up to 2 decimal places.

Your calculation

Choose Calculate to see the result. Changing an amount clears the previous calculation.

Formulas used by this calculator

Contribution before acquisition = retained first-order revenue − non-acquisition variable costs
Allowable total CAC = contribution before acquisition − contribution to retain
Media-only CAC allowance = allowable total CAC − other acquisition costs per new customer

Worked example

Illustrative first-order revenue: $120. Non-acquisition variable costs: $70. Required retained contribution: $20. Other acquisition costs per new customer: $8.

Contribution before acquisition is $50. Keeping $20 leaves an allowable total CAC of $30.

After $8 of other acquisition costs, $22 remains for media. A $28 media-only CAC would exceed this scenario's media allowance even though it is below the $30 total ceiling.

Start with a real new-customer definition

Use a cohort of newly acquired customers and their first eligible orders. Do not treat every order as a new customer. Repeat purchases, duplicate customer records, and canceled orders can distort a model whose denominator is intended to describe acquisition.

Use a consistent retained-revenue definition and relevant serving costs. A promotion cohort may have a different first-order contribution from a regular-price cohort. If the difference matters to a budget decision, model them separately rather than assuming one average describes both.

Keep total acquisition cost and media cost distinct

Stripe describes CAC as sales and marketing acquisition costs divided by newly acquired customers. Media is one part of that cost scope. This calculator estimates an affordable ceiling from first-order economics; it does not calculate observed CAC from a spending ledger. Stripe: defining and calculating CAC.

Enter serving costs in the non-acquisition variable-cost field. Allocate the included sales, creative, agency, and software acquisition costs to the other-acquisition field on a per-new-customer basis. Keep those costs out of the serving-cost field so they are deducted once.

The contribution-to-retain field represents what the business needs to keep after acquisition. It may support overhead or another operating objective, but it should not duplicate acquisition costs entered separately. The total CAC ceiling and the media-only allowance answer different questions and are labeled separately in the result.

Understand what a negative allowance means

If the first order cannot support the requested reserve and other costs, the model reports a shortfall. Zero is the boundary at which no positive media allowance remains. Negative output is useful evidence about the assumptions; it is not a recommendation to spend a negative amount.

A first-order model deliberately excludes uncertain future purchases. If the business accepts a first-order loss because customers are expected to return, build a separate cohort-based contribution and payback scenario. Keep cash timing, retention, and the uncertainty of that future contribution visible.

The SBA's contribution and break-even guidance provides context for separating variable costs and retained contribution. The acquisition ceiling here is an original planning application of those economics, not a target prescribed by the SBA. U.S. Small Business Administration: contribution and break-even analysis.

Use the result in a budget discussion

Compare the modeled media allowance with a compatible media-only cost per new customer. Compare the total ceiling with a fully scoped acquisition cost. Mixing the two can make a campaign appear affordable while leaving creative, sales, or software costs uncovered.

Save the worksheet with cohort dates, revenue treatment, and cost allocations. Refresh the inputs when pricing, fulfillment, return behavior, or the offer changes. A ceiling from an old product mix should not silently become a permanent campaign instruction.

Common questions

Is allowable CAC the same as actual CAC?

No. Allowable CAC is a modeled ceiling under your assumptions. Actual CAC divides the acquisition costs you incurred by the newly acquired customers under a defined scope and period. The calculator does not estimate how many customers a campaign will acquire.

Can I enter zero for other acquisition costs?

Yes, if those costs are genuinely outside the model or absent. State that scope clearly. Do not use zero simply to hide expenses that should be included in the acquisition decision.

Can the result be used as a platform CPA target?

Only after reconciling the event and cost definitions. A platform conversion may be a lead, order, or repeat purchase rather than a newly acquired customer. A media-only planning allowance is not automatically a suitable bidding target.