ACOS or TACOS: which number tells you whether your Amazon ads are working
ACOS divides your ad spend by the sales the ads brought. TACOS divides the same spend by all your sales, organic ones included. ACOS tells you how efficient the ads are. TACOS tells you how much of your whole business you hand back to advertising.
Every claim below points at a number we checked on real accounts: 12 seller and marketplace pairs (one brand on one Amazon marketplace) in Europe and the US. We compared Sponsored Products spend and ad-attributed sales with the total ordered sales from the Business Report, in four 30-day windows that do not overlap, from June 7 to October 4, 2026. The main comparison uses the August 6 to September 4 window, where the ad attribution is already final.
The link between the two
TACOS is ACOS multiplied by the share of your sales that came through ads. If ads brought 40% of your sales at 30% ACOS, your TACOS is 12%.
That share is the part ACOS cannot see. In the August window it ranged from 22% to 60% in 10 of the 11 pairs that advertised. So the same ACOS can mean very different things.
Same brand, same ACOS, more than twice the TACOS
One brand sold on two marketplaces. In the same 30 days its ACOS was 32.2% on one and 31.7% on the other. On ACOS alone, the two looked the same.
Their TACOS was 7.9% and 18.6%. On the first marketplace ads brought 24.6% of the sales, on the second 58.5%. The first one sells mostly on its own and ads add to it. The second one depends on ads for most of its sales, so a price change or a budget cut hits it much harder.
The ACOS ranking is not the TACOS ranking
We ranked the 11 pairs by both numbers in the same window. The one with the best ACOS (21.5%) was second by TACOS. The one with the best TACOS (7.9%) was only third by ACOS. The second-best ACOS dropped to fifth place by TACOS.
If you compare your marketplaces or products by ACOS only, you reward the one that already sells through ads, and you miss the one where ads are a small extra.
They often move in opposite directions
Across the four windows we had 33 month-to-month changes. In 9 of them ACOS and TACOS moved in opposite directions.
The clearest case: in one account ACOS fell from 130.6% to 80.9% in a month, which looks like a big improvement. TACOS rose from 29.5% to 45.4% at the same time. The ads did get more efficient, but sales outside the ads fell from 192 to 135 in the account's currency. The ACOS report showed progress, while the business was getting more dependent on ads.
The opposite also happens, and it can be healthy. In another account the ad spend nearly doubled from June to August, while total sales grew 2.6 times. TACOS fell from 11.2% to 8.4%. A rising budget is fine as long as total sales grow faster.
Read the two together
| ACOS | TACOS | What it means |
|---|---|---|
| down | down | Each ad sale is cheaper, and ads weigh less on your total sales too. |
| down | up | Each ad sale is cheaper, but a larger share of your sales now comes through ads, so the organic share is shrinking. Check ranking, stock, price and the Buy Box before celebrating. |
| up | down | Each ad sale costs more, but a smaller share of your sales depends on ads. If total sales are growing, this is acceptable during a launch or when scaling. |
| up | up | Each ad sale costs more, and ads cost more against your total sales too. Cut or restructure. |
Two things that skew the numbers
The windows have to match. Take total sales and ad spend for exactly the same days. The Business Report counts sales by order date, ad reports credit the sale to the click. Ad-attributed sales of the last 7 days are not final yet, so leave the last week out of a monthly comparison.
The two sales numbers are counted differently. Ad-attributed sales can include other products of yours that the buyer bought after the click. On a small marketplace this can push ad sales above total sales: one pair in our data had ad-attributed sales of 146% of its total sales in a month. When that happens, the ad share is not real, and TACOS is the safer number to watch.
Our numbers count Sponsored Products spend only. If you also run Sponsored Brands or Sponsored Display, add their spend to TACOS too.
What TACOS should be
There is no universal good TACOS. It comes from your own margin. Take what a sale leaves you after the product cost, Amazon fees and shipping, as a percentage of the price. Subtract the profit you want to keep. What remains is the most your TACOS can be. With a 35% margin and 15% target profit, that is 20%.
Ten minutes a month
Download the Business Report and the Sponsored Products advertised product report for the same 30 days, ending a week ago. For each marketplace write down three numbers: ACOS, TACOS, and the share of sales that came through ads. Compare them with last month and place each marketplace in the table above. Act on the rows where ACOS and TACOS disagree, those are the ones the ACOS report alone would hide.