运营者术语表

CPA（cost per acquisition，获客成本）

CPA 就是广告花费除以归因订单数，算出来是「每单多少钱」而不是百分比，所以它能直接对着单件毛利设上限，也能拿去跟 Meta、Google 的数字横着比。

CPA = ACoS × AOV = AOV ÷ ROAS，三个数其实是一个数，ACoS 和 ROAS 互为倒数；只有 CPA 是「每单多少钱」，才能对着单件毛利额设上限。坑在于公式里的 AOV 必须是广告归因销售额 ÷ 广告归因订单数，拿全店 AOV 代进去算出来的没有意义。更麻烦的是 Sponsored 广告不给这一列：Ads API v3 字段表里 SP、SB、SD 都没有 cost-per-purchase，eCPP 和一堆以 CPA 结尾的字段只有 DSP 才有；DSP 之外只有 benchmarks 报告给你自己品牌一个「每单获客成本」，但颗粒度只到品牌和类目，落不到广告活动、广告组或关键词。其余场景全靠手算，而分母会随归因窗口和计费方式变，比数之前先把窗口锁死；拉新预算看 NTB CPA——SB/SD 要自己除，SP 干脆没有。

关键数字

费率与规则以官方英文原文为准，保留原文：

In the Amazon Ads API v3 column reference, no cost-per-purchase column is available on any Sponsored Products, Sponsored Brands or Sponsored Display report type — NewToBrandECPP and the twelve columns literally named CPA are listed only on DSP report types.
Attribution windows differ: Sponsored Products gives sellers 7 days, clicks only, last click, and gives vendors 14 days with brand halo, while Sponsored Brands, Sponsored Display, Streaming TV and Amazon DSP use 14 days, so CPA denominators are not comparable until the window is pinned.
New-to-brand metrics are available on Sponsored Brands and Sponsored Display only — Amazon states new-to-brand data isn't available for Sponsored Products — and the published SB and SD metric list has no cost per new-to-brand purchase, so that CPA is a hand calculation over newToBrandPurchases.

官方来源：Ad campaign attribution - Amazon Ads Support Center · Amazon Ads API v3 reporting columns reference · Benchmarks reports - Amazon Ads API v3