ACoS, TACoS and ROAS: What Each One Answers
Three ratios, three different questions, and an account judged on the wrong one will optimise itself into a smaller business.
Three ratios get quoted interchangeably in Amazon accounts and they answer different questions. Using the wrong one is not a reporting problem, it is a strategy problem, because whichever number is on the dashboard is the number the account gets optimised towards.
The short version: ACoS judges a campaign, TACoS judges the business, and ROAS is ACoS the other way up for people who came from other channels.
ACoS: Advertising Cost of Sale
Ad spend divided by the sales that advertising produced. It answers whether a campaign paid for itself, and only that.
It is the right number for a bid decision and the wrong one for a budget decision, because it takes no account of the organic sales the advertising caused. A campaign at 40% ACoS that lifts a listing into the first page has done something the ratio cannot see.
ROAS: Return on Ad Spend
Sales divided by spend, which is the reciprocal of ACoS. A 25% ACoS is a 4x ROAS, and neither says anything the other does not.
It exists on Amazon because everybody arriving from Google and Meta thinks in ROAS. Pick one and use it consistently; using both is how two people in a meeting disagree about an account they both understand.
TACoS: Total Advertising Cost of Sale
Ad spend divided by total sales, organic included. It is the only one of the three that says whether advertising is building a business or renting one.
Rising sales with a falling TACoS means organic is growing faster than the spend: the advertising is doing its job and the listing is carrying more of its own weight. Rising sales with a rising TACoS means the growth is bought, and it stops when the spend does.
That distinction is invisible in ACoS, which is why an account can look healthy campaign by campaign while becoming more dependent on advertising every month.
The Window Behind Every Number
All three ratios depend on which sales the advertising is allowed to claim, and that is set by an attribution window rather than by anything that happened in the shop. A sale is credited to an ad if it follows a click within a set number of days, and the window differs by ad type. The console's own column names say which applies: a column called 7 Day Total Sales is exactly what it says.
Two things follow. The first is that the most recent week always looks worse than it will, because sales are still arriving against clicks already paid for, so a bid cut on yesterday's ACoS is a cut made on unfinished data. The second is that comparing ACoS between two ad types with different windows compares a shorter claim with a longer one, and the longer window flatters its campaigns.
The reports also split the sales an ad claims into the product advertised and other products from the same brand bought after the click. An ad that sells a different item has still earned its sale, and an ACoS calculated on advertised products alone undercounts it. For a brand with a range, the other products column is often where a campaign's real value sits.
This is also why two reports of the same campaign rarely agree: they often use different windows, or were pulled on different days before the late sales arrived. Agree which window the monthly report uses, write it on the report, and keep it.
All Three on One Product, Worked Through
Illustrative figures for one product over two months, to show what each ratio says and what only the three together reveal.
Month one. Advertising spend $1,500. Sales the advertising claims, $6,000. Total sales, organic included, $15,000. ACoS is 1,500 divided by 6,000, 25 percent. ROAS is the same thing upside down, 4. TACoS is 1,500 divided by 15,000, 10 percent.
Against break even. The product keeps 40 percent of its price before advertising, so its break even ACoS is 40 percent. At 25 percent, the advertised sales make money.
Month two. Spend rises to $2,000. Advertised sales rise to $7,000, so ACoS worsens to about 28.6 percent. Total sales rise to $20,000, so TACoS holds at 10 percent.
What ACoS alone would say. The campaigns got less efficient. A team judged on ACoS would cut the extra spend.
What the three together say. Total sales rose by a third while the share spent on advertising stayed the same. Organic sales, total minus advertised, rose from $9,000 to $13,000. The extra spend bought rank and visibility that sold more without ads. Cutting it would have saved a little and cost more.
The reverse case. Had total sales stayed at $15,000 while spend rose, TACoS would have risen to about 13 percent: the same ACoS story, and a genuinely worse month. Only the second ratio tells the two apart.
Why a Falling ACoS Is Sometimes Bad News
The fastest way to cut ACoS is to stop bidding on anything that does not convert immediately, which usually means brand terms and bottom of funnel keywords only.
Do that and the ratio improves while the top of the funnel disappears. Three months later the organic rank has slipped, the new customer count has fallen, and nobody can point at the change that caused it because the reporting looked better every week.
This is the single commonest way an account is optimised into decline, and it is the reason TACoS belongs on the same page as ACoS.
Which Number for Which Decision
Bid and keyword decisions: ACoS, at the search term level, with enough clicks behind it to mean something.
Budget and channel decisions: TACoS, over a quarter, alongside total sales.
Talking to somebody from outside Amazon: ROAS, because it is the language they already have.
Deciding whether the business is profitable: none of the three. That is contribution margin after fees, storage, returns and the cost of goods, which is a different calculation entirely.
The Break Even, Which Is the Only Target That Means Anything
Break even ACoS is your contribution margin as a percentage of price. Above it you are buying revenue at a loss; below it you are making money on the marginal sale.
That number is specific to your product and nobody else's benchmark applies to it. A 15% ACoS is disastrous on a product with a 12% margin and generous on one with 60%.
Which is why a target handed over without seeing the margins is a guess, and why the first thing worth doing in any account is working out what break even actually is per product. Benchmarks by channel are in the ROAS standards article, with the same caveat.
Reading Organic Sales Honestly
TACoS is useful because it brings organic sales into view. Organic is usually worked out as total sales minus the sales advertising claims, and that subtraction has limits worth knowing before drawing conclusions from it.
Some organic sales were helped by ads. A shopper who saw an ad, did not click it, and later searched for the product and bought it is counted as organic. Advertising lifts organic sales in ways attribution does not record, which is part of why TACoS matters.
Some advertised sales would have happened anyway. A shopper who searched for the brand by name and clicked a brand ad would probably have bought from the organic listing just below. Those sales inflate the advertised figure and shrink organic.
The window moves the split. A longer attribution window gives advertising more sales and organic fewer, without anything changing in the shop. Keep the window the same when comparing months.
Outside traffic counts as organic. Sales from social posts, email or the brand's own site arrive as organic on Amazon unless they are tracked with Amazon's attribution tools. A spike in organic may be a newsletter, not a ranking gain.
Read the trend, not the month. Because the split is approximate, a single month's organic figure proves little. Organic rising over several months while TACoS falls is the pattern that means advertising is building something.
Check against rank. Organic growth should show in the product's rank for its main terms. If organic rises and rank does not, look for the outside traffic.
TACoS Belongs to a Product, Not the Account
An account TACoS is an average, and averages hide the products that matter most. A mature product carrying strong organic rank might run at a low single figure TACoS while a launch beside it runs at many times that, deliberately, because it is buying the reviews and the rank it does not yet have. Put together, the account number looks moderate and says nothing true about either.
So the useful report is TACoS by product, over time, with the stage each product is in written beside it. A launch should start high and fall month on month as organic sales arrive; one that is still high after three months is a product the advertising cannot carry. A mature product should stay low and flat; one where it is rising is losing organic rank to somebody, and the advertising is filling the gap at a cost.
The same thinking applies to spend at the margin. The average ACoS of a campaign is not the cost of its next sale. The cheapest conversions are bought first, so each extra amount of budget buys sales at a worse rate than the average shows, and a campaign averaging comfortably under break even can be losing money on its last tenth of spend. Raising a budget is a decision about that last tenth, not about the average.
The monthly report that follows from this is short: total sales and TACoS by product, ACoS by campaign against each product's break even, and a line on which products moved stage. Anything more is usually detail somebody asked for once and nobody has read since.
A Monthly Report That Uses All Three
A report built around the right numbers changes what the people reading it decide. A simple layout, product by product, keeps each ratio in its place.
The columns. Total sales. Advertising spend. Sales the advertising claims. ACoS. TACoS. Contribution after advertising, the margin the product actually earned once the advertising was paid. And each product's break even ACoS beside its actual one.
The order of rows. Products sorted by contribution after advertising, so the ones that earn the most sit at the top and the ones losing money are easy to find at the bottom.
A line of commentary per product. What changed and why: a deal, a stockout, a new competitor, a budget change. Numbers without the reason invite the wrong conclusion.
The account line last. Total sales, total spend and overall TACoS, read as the sum of the products above it rather than as a target in its own right.
Three questions to answer each month. Is any product's ACoS above its break even, and is that deliberate? Is TACoS falling where advertising is meant to be building organic sales? Which products earn the most after advertising, and do they get the budget their returns justify?
The same layout every month. A report whose shape stays the same lets the reader see movement at a glance, which is most of what a monthly report is for.
What We Do With This
Reporting starts from contribution margin and carries all three ratios as context, which is part of Amazon account management rather than a separate analytics exercise.
The same distinction exists on Walmart and in Google Ads, where the platform's own return figure is similarly happy to look excellent while the business does not grow.
If nobody has worked out your break even per product, that is the place to start.
Frequently Asked Questions
The questions that come up most often on this subject.
Below your break even, which is your contribution margin as a percentage of price. That number is specific to the product: 15% is disastrous on a 12% margin and generous on a 60% one. Any target quoted without seeing your margins is a guess at the most important input.
Total advertising cost of sale: ad spend divided by total sales, organic included. It is the only one of the three ratios that says whether advertising is building a business or renting one, because it is the only one that can see the organic sales the advertising caused.
They answer different questions. ACoS is the right number for a bid or keyword decision; TACoS is the right number for a budget or channel decision. An account judged only on ACoS can look healthy campaign by campaign while becoming more dependent on advertising every month.
With sales rising, it means organic is growing faster than the spend, which is advertising doing its job. With sales flat it means you are spending less and selling the same, which may be efficiency or may be a top of funnel you have quietly switched off.
Take the selling price, subtract the cost of goods, the referral fee, fulfilment, and the share of returns and storage the unit carries. What is left, as a percentage of the price, is break even ACoS. Above it the marginal sale loses money.
Because ACoS knows nothing about your costs. It compares spend against advertising revenue, not against margin, so a product with thin margins can post an excellent ratio and lose money on every unit. Profit is contribution margin after every cost, and that is a different calculation.
Not on the ratio alone. A campaign at a high ACoS that is lifting a listing's rank is buying something the ratio cannot see, and cutting it is the commonest way an account is optimised into decline. Look at what happened to total sales and to TACoS before deciding.
It is the same relationship the other way up: 25% ACoS is 4x ROAS. It exists in Amazon conversations because people arriving from Google and Meta think in ROAS. Pick one and be consistent, because using both is how two people disagree about an account they both understand.
There is no universal figure, and the direction matters more than the level. A mature catalogue with strong organic rank runs a lower TACoS than one launching products, and a rising TACoS during a launch is expected rather than alarming. What matters is whether it falls as the listings mature.
All three, with contribution margin above them. The ratios are context; the margin is the verdict. A report that leads with ACoS invites the decision that improves ACoS, which is not always the decision that grows the business.