ACoS compares ad spend to ad-attributed sales only. TACoS compares the same spend to total sales, organic included. ACoS tells you whether a campaign is efficient; TACoS tells you whether advertising is building a business. Read them together — falling TACoS with steady ACoS is the signal that organic rank is compounding.
What each metric actually measures
Both metrics divide the same numerator — advertising spend — by a different denominator.
ACoS (Advertising Cost of Sale) divides ad spend by the sales Amazon attributes to those ads. Spend €1,000, get €4,000 of ad-attributed sales, and ACoS is 25%.
TACoS (Total Advertising Cost of Sale) divides the same €1,000 by total sales for the period — ad-attributed and organic together. If that same period produced €10,000 of total revenue, TACoS is 10%.
The gap between the two numbers is the whole story. A narrow gap means almost every sale is bought. A wide gap means organic demand is doing real work.
Why ACoS alone misleads you
ACoS is blind to everything outside the ad. That creates two failure modes we see on almost every account we inherit.
The first is the efficiency trap. A previous agency reports ACoS falling from 30% to 18% quarter over quarter. It looks like progress. What actually happened is that they cut every campaign that was not immediately profitable — including the ones defending top-of-search on the brand’s best keyword. Rank slid, organic sales followed, and total revenue fell 20%. ACoS improved the whole way down.
The second is the launch panic. A new SKU runs at 60% ACoS in week three and someone kills the budget. But during a launch there are no organic sales yet, so every sale has to be bought. The 60% was not waste — it was the price of the rank that would have produced organic sales in month three.
In both cases ACoS answered the question it was asked. It was the wrong question.
What TACoS tells you that ACoS cannot
TACoS answers a different question: is advertising building something that keeps selling when the ads stop?
Because the denominator includes organic sales, TACoS falls whenever organic revenue grows faster than ad spend. That is exactly the compounding you are paying for. Rank improves, the organic share of sales rises, the same ad budget covers a larger business, and TACoS drops without anyone touching a bid.
It also catches the opposite. Flat TACoS across two quarters of growing spend means you are buying incremental revenue at a constant rate — the account is scaling, but it is not compounding. That is a legitimate strategy for a commodity SKU with no defensible rank. It is a bad surprise for a brand that thought it was building one.
How to read the two together
Neither number means anything alone. The combination does.
| ACoS | TACoS | What it means |
|---|---|---|
| Flat | Falling | Organic rank is compounding. Keep going. |
| Falling | Rising | Campaigns look efficient but total sales are shrinking. Check what was cut. |
| Rising | Falling | Launch working as intended — paying for rank, rank is paying back. |
| Falling | Falling, with revenue down | Spend cut, demand lost. This is a retreat, not an optimisation. |
| Rising | Rising | Spend is outrunning results. Stop and audit before adding budget. |
The fourth row is the one that gets misread most often, because two metrics moving in the “good” direction feels like success. Always read TACoS next to absolute revenue.
The targets we actually use
We set break-even ACoS per SKU from the real contribution margin — price minus COGS, referral fee, FBA fee, inbound freight and returns provision — and then place the target relative to it by lifecycle stage.
- Launch (weeks 1–12): ACoS above break-even is expected. The number to watch is TACoS trending down week over week.
- Growth: ACoS at or slightly under break-even, TACoS falling toward 10–12%.
- Mature: ACoS 15–25% depending on category, TACoS steady in the 5–10% band.
- Defence: on a SKU under attack, we accept a worse ACoS on branded and top-of-search placements. Losing the top slot costs more than the bid does.
Every one of those is a per-SKU number. Blended account-level ACoS is a reporting convenience, not a decision-making tool — it averages a hero product that could take more budget together with a long tail that should be paused, and it recommends neither.
Frequent questions
What is a good ACoS on Amazon?
There is no universal number — a good ACoS is one below your break-even ACoS, which is your contribution margin before ad spend. If 32% of the sale price is left after COGS, fees and shipping, then a 32% ACoS breaks even and anything under it is profit. Mature SKUs typically run 15–25%; launches routinely run above break-even on purpose.
What is a good TACoS?
For an established catalogue, 5–12% is a healthy band. Above 15% usually means organic rank is not carrying its share and the brand is renting its sales from advertising. Below 5% often means you are underinvesting and leaving rank on the table for a competitor to take.
Should I optimise for ACoS or TACoS?
Optimise campaigns on ACoS and judge the strategy on TACoS. ACoS is the lever you can pull this week — bids, placements, negatives. TACoS is the quarterly scoreboard that tells you whether those levers are producing a business that would still sell if you paused the ads.
Does TACoS work as a metric during a launch?
It works, but read it as a trend and not as a level. A launch starts with TACoS of 30% or more because there are almost no organic sales to dilute the spend. What matters is the slope: eight to twelve weeks in, TACoS should be falling week over week. If it is flat, the product is not gaining rank and the spend is not compounding.