Amazon does not surface Customer Acquisition Cost (CAC) the way a DTC storefront (Shopify, WooCommerce) does — on those platforms the seller owns the full funnel end-to-end. On Amazon the underlying data exists but is scattered across three separate systems, so CAC has to be approximated by combining:
Blended CAC = Ad Spend / (Total Orders − Repeat Unit Orders)
This is a "true"/blended CAC because it captures customers acquired both through ads and organically — conceptually the same lens as TACOS vs. ACOS (Total Advertising Cost of Sale as a blended efficiency measure). In a worked example this formula came out to roughly 446.
Three ways to approximate the paid-only figure, all imperfect:
Ad Spend / (Total Orders − Advertised Orders), assuming repeat purchases aren't ad-driven.CPC × Total Clicks = Ad Spend, then combine CPC with conversion rate directly (e.g., $1.37 CPC against a 14.05% conversion rate over 961 total clicks) to reach advertised CAC without pulling separate order counts.Consumer Behavior Analytics (Repeat Purchase Behavior Report) and the advertising new-to-brand metric define "new" customer differently (90-day repeat window vs. 365-day new-to-brand lookback), so none of the above formulas reconcile to a single precise number — only an approximation.
My Amazon Guy has in-house software (not sold publicly) that automates pulling all of these reports and calculating true per-product profit margin and CAC, aimed at repeat-purchasable CPG brands.
Metric to use: base all CAC math on Units Ordered, not Total Order Items — Units Ordered is the actual unit count sold, distinct from Total Order Items, a metric sellers often mistake for it.
Blended CAC = Ad Spend ÷ (Total Orders − Repeat Unit Orders). Total Orders and Repeat Units come from the Consumer Behavior Analytics (Repeat Purchase Behavior Report) (Customer Behavior Analytics → Repeat Purchase Behavior, by ASIN or brand). Netting repeat units out of total orders approximates new customers; dividing total ad spend by that count gives a blended organic+paid CAC (~$4.46 in one seller's example). Conceptually adjacent to TACOS (TACOS vs. ACOS).
Advertised CAC = Ad Spend ÷ (Total Orders − Advertised Orders) — swaps in Advertised Orders for Repeat Units, assuming repeat purchases aren't ad-driven, to isolate an ads-only CAC instead of the blended figure.
CPC × conversion-rate shortcut: an alternative route to advertised CAC using only Cost Per Click, Total Clicks, and Conversion Rate from the advertising report (CPC × Total Clicks = Ad Spend, related back through the conversion rate) — skips manually pulling order counts.
Cross-check, not proof: the Sponsored Brands new-to-brand order line item (unavailable for Sponsored Products) is the closest thing Amazon offers to a true paid CAC, but it excludes Sponsored Products spend, so no single report yields a fully accurate paid-only CAC.
Why it's an approximation: Brand Analytics counts a purchase 'repeat' only within a 90-day window, while Advertising's new-to-brand definition uses a 365-day lookback — a customer counted 'new' by one system may already be 'repeat' by the other, so any of these cross-report CAC formulas is inherently an approximation.