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ACoS vs. TACoS: Which Amazon Ad Number Actually Matters

ACoS tells you about ads. TACoS tells you about the business. How to calculate both, what a good number looks like, and what owners should watch.

David LedbetterChief Growth Officer

Published Oct 2, 2026Updated Oct 2, 20263 min read

Analytics charts and graphs on a laptop screen

If you only look at one Amazon ad number, it’s probably ACoS. It’s the default in every report. It’s also the number most likely to make a struggling account look healthy.

The two formulas

ACoS = Ad spend ÷ Ad-attributed sales × 100

TACoS = Ad spend ÷ Total sales × 100

Example: you spend $10,000 on ads in a month. Amazon attributes $40,000 in sales to those ads. Your total Amazon sales were $100,000.

ACoS = 25 percent
TACoS = 10 percent

What each one tells you

ACoS measures ad efficiency. For every dollar of ad-attributed sales, how much did you spend? It’s useful for managing individual campaigns and keywords.

TACoS measures how dependent the whole business is on advertising. It answers the question owners actually care about: are the ads growing the business, or just buying the same sales at a higher price?

How to read them together

ACoS	TACoS	What it usually means
Steady	Falling	Ads are working. Organic sales are growing faster than ad spend.
Steady	Rising	You’re becoming more ad-dependent. Organic isn’t keeping up.
Falling	Rising	Campaigns look efficient, but the business relies on them more. Often branded spend.
Rising	Rising	Spending more to get less. Time to look underneath the ads.

If TACoS keeps climbing while revenue is flat, read why Amazon ad spend keeps rising while sales stay flat.

What’s a good ACoS?

There’s no universal number. It depends on your margin. Start with your break-even ACoS: your profit margin before ad costs. If a product makes 35 percent before advertising, an ACoS above 35 percent loses money on every ad sale. A good target sits comfortably below break-even, adjusted for whether you’re launching, defending, or harvesting.

What neither number tells you

Neither accounts for your full costs: COGS, FBA fees, returns, storage. And ACoS can’t tell a branded sale you’d have gotten anyway from a new customer. See branded vs. incremental sales. That’s why we report profit per product in dollars, tied to your real landed costs, in one page a month your controller can reconcile.