ACOS vs TACOS: the number most Amazon brands are optimizing the wrong way

Almost every brand owner we speak to knows their ACOS. Far fewer know their TACOS, and fewer still know their break-even ACOS, which is the number that decides whether either of the first two is good news.

This is not pedantry. Choosing the wrong headline metric leads to a specific, predictable mistake: cutting spend on campaigns that were working.

What each number actually measures

ACOS is ad spend divided by ad-attributed revenue. It answers: of the sales my ads produced, what share did I pay Amazon to produce them?

TACOS is ad spend divided by total revenue, organic and paid together. It answers a bigger question: how dependent is this brand on advertising at all?

Break-even ACOS is your gross margin percentage after Amazon fees, COGS and freight. It is the line where an incremental advertised sale makes exactly zero profit.

The first is a campaign metric. The second is a business metric. The third is the context that makes the first two mean anything.

Why a low ACOS is often a bad sign

We took over an account last year running at 9% ACOS. The previous manager was proud of it, and on paper it looked excellent.

What was actually happening: bids were set so low that the campaigns only won the cheapest, least competitive auctions, mostly branded searches from people who were already looking for the product by name. The ads were harvesting demand that would have converted anyway, and were invisible on every competitive category term.

Meanwhile total revenue was flat and had been for three quarters. The ads were efficient at doing nothing.

• Very low ACOS with flat revenue usually means under-bidding, not efficiency
• Rising ACOS with rising total revenue is often exactly what you want during a push
• Rising ACOS with flat revenue is the genuinely bad one, you are paying more for the same sales

The pattern to actually watch

The signature of advertising doing its real job is TACOS falling while total revenue rises.

That combination means ads drove sales velocity, velocity lifted organic rank, and organic sales are now carrying a growing share of the total. You are buying your way into a flywheel rather than renting position indefinitely.

It is also much harder to fake than ACOS. An agency can drop ACOS in a week by cutting spend on everything competitive. Getting TACOS down while revenue grows takes actual work over a quarter, which is why we report on it and why we would suggest holding any partner to it.

What to do differently on Monday

• Calculate break-even ACOS per ASIN, not per account. Two products at the same ACOS can be one profitable and one losing money, purely because their cost structures differ.
• Stop setting blanket ACOS targets across a catalog. They are meaningless without margin context.
• Pull the last six months of total revenue against total ad spend and plot TACOS. The trend line tells you more than any single month's ACOS ever will.
• Before cutting a campaign for high ACOS, check whether the ASIN's organic rank has been improving. If it has, the campaign is doing its job and cutting it will cost you the rank you paid for.

Where this fits with how we work

We buy our brand partners' products at wholesale, which means we are spending our own money on advertising against inventory we already own. That changes the incentive completely: we cannot afford to optimize for a flattering ACOS screenshot, because the stock still has to sell.

If you want a second read on what your numbers are actually saying, send them over. We will tell you what we see, whether or not you ever work with us.