Short version: ACOS is ad spend divided by ad-attributed sales, times 100. Amazon's own advertising guidance is explicit that there's no universal "good" number — what matters is your own break-even ACOS, which is set by your profit margin, not by an industry average. Set that number from your own numbers first, then use it to decide which bids to cut and which campaigns are allowed to run over it on purpose.
Every Amazon seller running Sponsored Products ends up asking the same question sooner or later: is my ACOS good or bad? The honest answer, straight from Amazon's own advertising guide, is that there's no single number to compare yourself against — it depends on your margin, your category, and what a given campaign is actually for. That's not a dodge; it's the correct answer, and it means the useful work is calculating your own target rather than hunting for someone else's benchmark. (New to Sponsored Products entirely? Our Amazon PPC strategy guide for beginners covers campaign types, targeting, and starting budget before ACOS becomes the question that matters.)
What is ACOS on Amazon?
ACOS stands for Advertising Cost of Sales. Amazon defines it as the percentage of ad-attributed revenue you spent on advertising to earn it, and the formula is:
ACOS = (ad spend ÷ ad revenue from that spend) × 100
Spend $30 on Sponsored Products and generate $150 in ad-attributed sales → ACOS = ($30 ÷ $150) × 100 = 20%.
Amazon's Advertising Console reports ACOS per campaign, ad group, and keyword/target directly — you don't need a separate calculator, since the spend and attributed-sales figures the formula needs are already sitting in your campaign reports.
ACOS vs. TACOS vs. ROAS
Two related metrics come up in the same conversations and are worth telling apart:
- TACOS (Total Advertising Cost of Sales) divides ad spend by your total sales — ad-driven and organic combined — instead of just ad-attributed sales. It's not in Amazon's console natively; you calculate it from your Business Reports and Advertising Reports together. TACOS is the number that falls over time as organic sales grow even while ACOS holds steady, which is why it's the better long-run health check for a whole account rather than a single campaign.
- ROAS (Return on Ad Spend) is Amazon's own inverse of ACOS — ad revenue ÷ ad spend — reporting the identical relationship the other way around. A 20% ACOS is a 5x ROAS.
What counts as a "good" ACOS? Amazon's own answer
Amazon's advertising guidance doesn't hedge on this: "There isn't a definitive number for a good Amazon ACOS. It's dependent on your industry, company size, and campaign frequency, among other variables." What it offers instead is a way to calculate your own number: "Break-even ACOS is directly linked to your profit margin. In order to maintain a profit, your Amazon ACOS needs to be lower than your profit margin."
In plain terms: figure out your profit margin on a sale before ad spend (price minus COGS, Amazon fees, and any other per-unit cost), and that percentage is roughly your break-even ACOS — the ceiling above which a sale funded by that ad click loses you money. To see that margin per SKU after fees, returns and ads, read how to see per-SKU profit on Amazon.
| Profit margin before ad spend | Approximate break-even ACOS | What it means |
|---|---|---|
| 15% | ~15% | Thin margin — very little room for ad spend before a sale stops paying for itself. |
| 25% | ~25% | Common for competitive categories; most keywords need to stay well under this to also cover non-ad overhead. |
| 40% | ~40% | Healthier margin — more room to run ads above pure break-even for growth, still with a real ceiling. |
| 55%+ | ~55%+ | High-margin listings can sustain a much higher ACOS and still turn a profit on the ad-driven sale itself. |
This is deliberately a rule of thumb, not an exact accounting model — it ignores repeat purchases, the organic-rank lift a sale can produce, and fixed costs that don't scale per unit. Use it to set a starting target per campaign, then adjust from what you actually see.
Worked example: setting a target ACOS
Profit before ad spend: $22 − $11 − $3.30 = $7.70, or 35% of the sale price. That 35% is roughly this listing's break-even ACOS.
A campaign running at 28% ACOS is under that line — profitable on the ad-driven sale itself, with room to raise bids and win more impressions. A campaign at 46% ACOS is over the line — every ad-driven sale is currently losing money once you count what it cost to win the click, so it's a candidate for a bid cut or a closer look at which search terms are driving that number up.
Why your target should change by campaign goal
A single break-even number isn't the whole strategy, because not every campaign is trying to turn a direct profit on day one:
- New-launch campaigns often run deliberately over break-even to win the reviews and sales velocity that drive organic rank — a cost sellers accept for a limited window, not indefinitely.
- Defensive campaigns bidding on your own brand or ASIN terms to keep a competitor's ad off your product page can justify a higher ACOS than a pure-profit campaign would.
- Mature, profit-focused campaigns on keywords that already convert well should be held closer to (or under) break-even, since there's no growth story left to subsidize.
The failure mode isn't running a campaign above break-even — it's doing that without deciding to, and without a plan to bring it back down once the reason for running it over is gone.
How to lower a high ACOS
- Cut bids proportional to the overage. A keyword running 50% over your target ACOS usually needs roughly a 50% bid cut to re-center — check again after a week rather than assume the math holds exactly.
- Add negative keywords. Search terms burning spend with zero orders after a reasonable click sample are the single biggest lever on a bloated ACOS — see our PPC audit checklist for the full process.
- Check placement bid multipliers. A "top of search" or "product pages" multiplier set once at launch and never revisited is a common source of ACOS drift that no single keyword bid explains.
- Raise conversion rate instead of cutting spend. A better main image, a title that actually says what the product is, or a price that matches the competitive set all raise the sales you get per click — which lowers ACOS without touching a single bid.
What the "25–40%" benchmarks you'll find elsewhere actually are
Search for "average Amazon ACOS" and most PPC agency and tool blogs converge on a range somewhere around 25–40%, with anything under 25% called excellent and anything over 40% called too high. That range shows up often enough that it's worth naming — but it comes from PPC agencies' and tool vendors' own client data or self-reported surveys, not from Amazon. Amazon's own position, quoted above, is that there isn't a definitive number, and the category spread agencies themselves report (higher for repeat-purchase categories like supplements, lower for tight-margin categories like electronics) is exactly why a single average is a weak thing to chase. Treat any published range as a sanity check at most, not a target — your own break-even ACOS is the number that actually tells you whether a campaign is profitable.
Automating ACOS fixes: what needs your approval every time
Once you know your target ACOS per campaign, the audit itself is mechanical — but not everything that follows from it should run unattended. Bid changes, budget changes, and pausing or enabling a campaign outside a rule you've already authorized all move money directly, so they come back to you for approval, item by item, no matter which tool suggests them. Bounded, reversible actions are different: dayparting on a schedule you choose, pausing ads while a product is out of stock, or exact-match negative keywords that match a rule you approve can run under a one-time standing authorization, each capped at a daily limit and revoked the moment you change the rule.
That's the split OptimalCentral's Ads Audit is built around: connect your Amazon Ads account and it returns bids running above your target ACOS — with a new bid it calculates from cost per click and your target — plus wasted spend and negative-keyword candidates, as a ready-to-review change list. On Pro, you download that as a change file to upload yourself; from Brand up, you can apply the changes you approve straight to your account, while the standing-authorization pieces run on their own and every bid, budget, or campaign-state change still waits for you.
Find every bid running above your target ACOS
Connect your Amazon Ads account and OptimalCentral's Ads Audit calculates a new bid for every keyword and target running over your target ACOS — you approve every change before it goes live.
See the Ads Audit →Once your bids are back under control, the rest of the audit — wasted spend, negative keywords, budget caps — is covered step by step in our Amazon PPC audit checklist. And since a listing that converts better needs less ad spend to hit the same ACOS, our complete guide to Amazon SEO covers the organic-side levers — title, images, backend keywords — that make every paid click work harder.
Frequently asked questions
What is a good ACOS on Amazon?
Amazon's own advertising guidance is direct about this: there isn't a definitive number, because it depends on your industry, company size, and campaign goals. What Amazon does say is that your ACOS needs to be lower than your profit margin to keep the sale profitable after ad cost — that margin is your break-even ACOS, and it's specific to your product, not a category average.
What is the ACOS formula on Amazon?
ACOS = (ad spend ÷ ad revenue) × 100, using only the sales Amazon attributes to that ad spend. Spend $30 on a campaign that generates $150 in attributed sales and your ACOS is 20%.
Is there an Amazon ACOS calculator?
Amazon doesn't publish a named "ACOS calculator" tool — the spend and attributed-sales figures you need are already in your Advertising Console's campaign reports, and the formula is one division. Amazon's own inverse metric, ROAS (ad revenue ÷ ad spend), reports the same relationship the other way around.
What's the difference between ACOS and TACOS?
ACOS measures spend against ad-attributed sales only. TACOS (total advertising cost of sales) measures spend against your total sales, ad-driven and organic combined, so it drops as your organic sales grow even if ACOS stays flat. Amazon's console reports ACOS natively; TACOS has to be calculated by hand from your Business Reports and Advertising Reports.
How do I lower a high ACOS on Amazon?
Cut bids on keywords and targets running well above your target ACOS, add the zero-order search terms burning spend as negative keywords, check placement bid multipliers for drift since launch, and improve the listing itself — a better main image, title, or price raises conversion rate, which lowers ACOS without touching a single bid.
Is a high ACOS always bad?
No. A launch campaign built to win reviews and organic rank, or a defensive campaign protecting your own listing from competitor ads, can be worth running above your break-even ACOS on purpose for a limited window. The problem is a high ACOS nobody set on purpose and nobody is tracking back down.