ACOS is ad spend divided by ad-attributed sales, so it only measures advertising in isolation. TACOS is ad spend divided by total sales including organic, so it measures what advertising costs your whole business. A falling TACOS with steady revenue means organic rank is carrying more of the load — that is the healthiest signal in an Amazon account.
How do ACOS and TACOS differ at a glance?
Both divide ad spend by sales — the difference is which sales sit in the denominator. ACOS uses only ad-attributed sales; TACOS uses every sale, paid and organic.
| ACOS | TACOS | |
|---|---|---|
| Formula | Ad spend ÷ ad-attributed sales | Ad spend ÷ total sales (paid + organic) |
| Measures | Efficiency of advertising in isolation | What advertising costs the whole business |
| Best for | Tuning bids, keywords and campaigns | Tracking overall ad dependence over time |
| A falling number means | Ads got more efficient — but can be faked by pausing non-branded campaigns | Organic rank is carrying more of the load — the healthiest signal in an account |
When does ACOS alone mislead you?
You can improve ACOS simply by switching off every campaign except your branded terms. ACOS drops beautifully and total sales fall off a cliff, because you stopped acquiring new customers.
ACOS answers 'were these ads efficient'. It cannot answer 'is the business growing', which is why it should never be read on its own.
What does a rising or falling TACOS tell you?
TACOS falling while revenue holds or grows means organic sales are increasing relative to paid — your ranking is improving and you are becoming less dependent on ads.
TACOS rising while revenue is flat means you are buying the same sales at a higher price. That is the early warning of listing decay or a new competitor bidding on your terms.
Want this checked on your own account?
The free audit answers this question with your numbers instead of general rules — no Seller Central password needed.
Get my free audit