Amazon ACOS vs TACOS vs ROAS: Which Metric to Use When

ACOS, TACOS, and ROAS measure different things. Here's exactly when to use each, what they hide, and the metric that actually predicts profit.

Article summary

ACOS, TACOS, and ROAS measure different things. Here's exactly when to use each, what they hide, and the metric that actually predicts profit.

ACOS: campaign efficiency

Three brands asked me the same question last month, phrased three different ways:

ROAS: the inverse framing

"Should I optimize to ACOS or ROAS?" "My agency reports TACOS but I don't understand it — is it better than ACOS?" "What's the difference between all these metrics and which one actually matters?"

TACOS: the whole-business metric

The confusion is understandable. Amazon advertising has three overlapping efficiency metrics, they measure related-but-different things, and most explanations online just define them without telling you when to use each.

The metric none of them capture: profit

This post fixes that. Here's what each metric measures, when to use it, what it hides, and the one I actually optimize toward.

When to use which — the decision guide

- ACOS = ad spend ÷ ad revenue. Measures campaign efficiency. Use for campaign-level bid decisions. - ROAS = ad revenue ÷ ad spend. The inverse of ACOS. Same data, framed for revenue thinking. - TACOS = ad spend ÷ total revenue (ad + organic). Measures whether ads are building the whole business. Use for account-health tracking. - None measures profit — you need contribution margin for that. - Use all three as diagnostics, optimize to none of them directly. Optimize to margin × velocity by campaign type.

Frequently Asked Questions

Formula: Ad spend ÷ ad-attributed revenue. If you spend $25 and generate $100 in ad sales, ACOS is 25%.

About the author

What it measures: How efficiently a specific campaign converts ad spend into attributed revenue.

Is ACOS or ROAS better for Amazon PPC?

They're identical data in different framing — ACOS is a cost percentage, ROAS is a return multiple. Use whichever helps you think clearly. Neither is "better." Both measure campaign efficiency and share the same blind spots (no profit, no incrementality, no organic impact).

What's more important, ACOS or TACOS?

For bid decisions, ACOS. For account health, TACOS. TACOS is the better big-picture metric because it captures whether your ads are building organic momentum. But neither should be your sole optimization target — profit metrics should drive strategic decisions.

What is a good TACOS for Amazon?

8-15% for a mature account, 15-25% during growth, 25-40% during launch. More important than the number is the trend — TACOS should decline over time as organic revenue grows faster than ad spend.