ACoS divides ad spend by ad-attributed sales, so it grades one traffic channel, while TACoS divides the same ad spend by total sales, so it grades all five. Divide TACoS by ACoS and you get the share of revenue advertising bought. The rest came from channels your ad report cannot see.
The short version
- ACoS prices the paid channel only. Ad spend over ad-attributed sales, with every other source of revenue left outside the ratio.
- TACoS prices the whole traffic system. The same spend over every dollar the brand sold in the period.
- The two ratios divide into one useful number. TACoS over ACoS returns the share of revenue that advertising bought.
- Two accounts at 30 percent ACoS can sit $4,800 a month apart in the margin they keep, on an identical revenue line.
- Five traffic channels exist and most sellers run two. ACoS can see one of the five, so it flatters a narrow account.
The arithmetic, written out
Both ratios share a numerator, which is the money you handed to Amazon advertising. Only the denominator changes, and the denominator is the whole argument.
Take one month on a mid-sized account. Total sales of $40,000, ad spend of $4,800, and ad-attributed sales of $16,000.
ACoS is 4,800 divided by 16,000, which is 30 percent. TACoS is 4,800 divided by 40,000, which is 12 percent. Same spend, same month, and two ratios that disagree by 18 points.
Now divide TACoS by ACoS. Twelve over thirty returns 0.4, so advertising bought 40 percent of the revenue that month.
The other 60 percent arrived without a click you paid for. No console prints that fraction for you, and it is the most useful number the pair produces.
What the same ACoS costs two accounts
ACoS cannot separate the two accounts below. Both report 30 percent, and they keep different amounts of money.
| Line | Account A | Account B |
|---|---|---|
| Total sales a month | $40,000 | $40,000 |
| Ad-attributed sales | $32,000 | $16,000 |
| Ad spend | $9,600 | $4,800 |
| ACoS | 30% | 30% |
| TACoS | 24% | 12% |
| Share of revenue advertising bought | 80% | 40% |
| Contribution margin before ads at 35% | $14,000 | $14,000 |
| Margin left after ad spend | $4,400 | $9,200 |
Account A keeps $4,400 and Account B keeps $9,200 on the same revenue line. That is $4,800 a month, or $57,600 a year, decided by a number the ACoS column never reports.
Both jobs are real work, and they are not the same job. GrillX, a BBQ and bar accessories brand we manage, moved ACoS from 88 percent to 32 percent, which is the Account A repair done properly.
Vora Bowl runs at 5.7 percent TACoS at scale, with six-figure monthly targets carried on $5,000 of monthly spend. The second number is harder to build, because most of it is produced outside the ad console.
Reading ACoS TACoS together on one account
The gap between the two ratios is a report card on your traffic mix. Five channels feed an Amazon listing: organic, paid, promotions, influencer and creator programs, and off-channel. Most sellers run two of them, organic and paid, so their TACoS sits close to their ACoS by construction.
That is the mechanism in one line. ACoS can price a single one of the five channels. TACoS is the only ratio that prices what the others produced, because their revenue lands in the denominator and never in the numerator.
Fifty operators here run about 70 brands by hand across all 23 Amazon marketplaces. The accounts with the lowest TACoS are not the ones with the cleverest bids. They are the ones where promotions, creators, and off-channel traffic carry sales that no ad report ever claims.
So the buying test writes itself. Ask anyone who wants to run your advertising which of the five channels they run on your account, and who runs each one.
Then watch the direction of the ratio month over month. Falling, with total sales flat or rising, means the other channels are taking weight. Rising means advertising is renting revenue that the rest of the system is not producing.
What an ads manager will not tell you about the two ratios
Which ratio reaches your inbox is a commercial decision before it is a technical one. Run the fee arithmetic and the reason shows up.
A fee set at 15 percent of ad spend earns $720 on Account B and $1,440 on Account A. Same schedule, double the income, and the account with the narrower channel mix is the one paying for it.
| Monthly ad spend | Fee at 15% of spend | Flat fee, one product |
|---|---|---|
| $4,800 | $720 | $800 |
| $9,600 | $1,440 | $800 |
Read the honest half of that table as well. At $4,800 of monthly spend the percentage model bills less than our flat fee does, so price is not the argument here.
Direction is. Our invoice does not move when your spend falls, and $800 a month for one product rising to $2,400 for five is the entire fee, with no commission on spend.
The second omission is ownership. TACoS moves on price, stock cover, reviews, creative, and season, so nobody holding only the ad console wants it inside their objectives.
Ask whoever runs your ads to accept it anyway, and to name the person responsible for every channel outside paid. If we cannot answer that on your account, do not hire us.
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This week, pull last month's numbers per product and run the one division nobody runs. Write TACoS over ACoS next to each ASIN, and the fraction tells you what share of that product's revenue your advertising bought. Everything above the line is what the rest of your traffic system produced, for free.
To have that division run across your catalog with the ranked fixes written up inside 48 hours at no charge, ask for the free audit at Flapen.
