C4 · Economics & metrics · ratio

Customer Acquisition Cost

Also: CAC

Definition. CAC allocates acquisition costs to acquired paying customers. A same-period S&M/new-logo ratio is a descriptive allocation; a cohort estimate aligns costs, acquisition timing and customer eligibility. Neither a single lag nor this ratio identifies the incremental effect of marketing.

established Last updated 2026-06-18 Source: Illustrative practitioner cost ranges; not verified current sample medians. Acquisition definitions, segment, geography, pricing, cost allocation and sales cycle must be matched.

Formula

Customer Acquisition Cost ratio

C A C = \frac{S&M opex + allocated overhead}{new customers acquired}

Plain English: CAC = Total Sales & Marketing spend / New customers acquired in the period

Notation: CAC = (S&M_opex + allocated_overhead) / new_customers_acquired

Benchmark by stage

Source: Illustrative practitioner cost ranges; not verified current sample medians. Acquisition definitions, segment, geography, pricing, cost allocation and sales cycle must be matched.

Stage	Customer Acquisition Cost	Notes
PLG / Self-serve	< $1,000	Illustrative planning band; compare matched customer segments and cost definitions, not a universal target.
Mid-market (inside sales)	$5,000–$50,000	Illustrative planning band; compare matched customer segments and cost definitions, not a universal target.
Enterprise (field sales)	$50,000–$500,000	Illustrative planning band; compare matched customer segments and cost definitions, not a universal target.
Best-in-class (any motion)	LTV:CAC > 3:1	Illustrative planning band; compare matched customer segments and cost definitions, not a universal target.

Naive vs corrected

Version	Formula
Naive	Counting only advertising while excluding acquisition headcount, tools, partners or other relevant costs; the size of the understatement is company-specific.
Corrected	Disclose which acquisition labor, tools, commissions and overhead are included, avoid double counting, separate new-logo from expansion costs, and align the cost window with the acquired cohort. Report cash and fully loaded economic costs separately when they differ.

Common errors

Excluding acquisition labor and channel commissions
Counting free users as acquired paying customers
Blending new-logo and expansion costs without disclosure
Assuming a one-quarter or average-cycle lag exactly matches the acquired cohort
Treating attributed acquisition cost as causal incremental CAC

Where this sits

Part of the Economics & metrics (C4) cluster in the GTM World Model. Related to the model's "Descriptive CAC = allocated acquisition costs / eligible acquired customers. Cohort CAC requires an explicit cost-allocation and timing rule; incremental CAC requires a causal incremental-customer denominator." equation.

ltv →ltv cac ratio →cac payback →magic number →

How to cite this

@misc{shalvi_gtm_metric_cac_2026,
  author = {Singh, Shalvi},
  title  = {Customer Acquisition Cost — GTM World Model Metrics},
  year   = {2026},
  url    = {https://shalvisingh.com/gtm/metrics/cac}
}

Singh, Shalvi. "Customer Acquisition Cost — GTM World Model Metrics." shalvisingh.com, 2026. https://shalvisingh.com/gtm/metrics/cac