Defining the Two Metrics

ACOS (Advertising Cost of Sale) is calculated as ad spend divided by ad revenue — the revenue that came directly from paid clicks. A 20% ACOS means you spent $20 in ads to generate $100 in ad-attributed revenue.

TACOS (Total Advertising Cost of Sale) is calculated as ad spend divided by total revenue — including organic sales. It measures the true cost of advertising as a percentage of your entire business on Amazon.

Why ACOS Alone Is Misleading

If you optimize purely for ACOS, you’ll make decisions that look efficient in the ads console but may be damaging your overall business.

• ACOS optimization can lead to under-investing in keywords that drive organic rank lift
• Cutting spend on broad awareness campaigns looks efficient in ACOS but collapses the top of funnel
• New product launches require accepting high ACOS temporarily to build velocity and BSR
• ACOS ignores the halo effect of ad impressions on organic conversion rates

When to Prioritize Each Metric

For new product launches and expansion into new keywords, ACOS is less useful because you’re deliberately sacrificing efficiency to build velocity, rank, and reviews. For mature, well-ranked products with stable organic velocity, ACOS becomes a reliable efficiency metric.

The Metric That Actually Drives Decisions

The most sophisticated Amazon advertisers use both together: TACOS as the top-level health indicator of their advertising program’s impact on total business performance, and ACOS as a diagnostic metric for individual campaigns and keywords. Track both, understand the relationship between them, and never make major budget decisions based on ACOS alone.