Can I Use CPA and ACoS Together in Amazon Ads?
← Back to Amazon Ads CPA vs ACoS: Which Metric Is Better for Optimisation?
Quick answer
CPA and ACoS can be used together in Amazon Ads to create a clearer picture of account performance. CPA measures the advertising cost attributed to a conversion, while ACoS expresses ad spend as a percentage of attributed sales. Tracking both metrics side by side helps advertisers see not only how efficiently spend produces revenue, but also what a customer acquisition actually costs. That combined view supports more precise decisions when product mix or business targets shift.
Using both metrics does not mean optimizing both aggressively at the same time. It means giving yourself two lenses on the same data. A campaign can have a strong ACoS but an expensive CPA, or the reverse, and that tension is usually where the most actionable insight lives.
What CPA and ACoS show when used side by side
ACoS answers a revenue-efficiency question: how much of each dollar earned goes back into ads. CPA answers a conversion-cost question: how much is being spent to produce a purchase or lead action. When one is improving and the other is flat, it often indicates a change in average order value, conversion rate, or traffic quality.
- Low ACoS but high CPA may mean orders are high value but conversions are rare or expensive to trigger.
- High ACoS but low CPA may mean conversions come cheaply but produce too little revenue relative to ad spend.
- Both moving together can confirm that a change in product pricing or targeting is affecting the full funnel.
A practical way to run both metrics without conflicts
Set one metric as the primary guardrail and the other as a diagnostic signal. For example, if profitability is the current goal, use ACoS as the main target and check CPA for unexpected cost-per-order drift. If the goal is customer acquisition volume, let CPA lead and watch ACoS to avoid overspending on low-margin products. This avoids the common mistake of pausing a keyword because one metric looks bad while the other tells a different story.
Using a read-only dashboard that consolidates spend, sales, ROAS, and ACoS can make this comparison more practical; for example, Amazon Ads Dashboard by Todoza supports cross-campaign trend checks without changing campaigns automatically.
When this matters
This dual-metric view is most useful when you are changing product mix, testing new keywords, or moving from a launch phase to a profit phase. During those transitions, a single metric can hide a problem. Watching CPA and ACoS together makes it easier to see whether higher ad cost is buying worthwhile orders or simply consuming margin. It is also helpful for agencies managing multiple accounts with different target ROAS thresholds, because the same ACoS number can mean very different things depending on the product price and repeat purchase behavior.
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Related guides
Whether you lean toward CPA, ACoS, or a blend of both, the goal is the same: understand how ad spend is performing before you change bids, targets, or negatives. For a broader look at choosing between these two optimisation metrics, revisit the main Amazon Ads CPA vs ACoS guide.