Key takeaways
- ACoS is advertising spend divided by ad sales, shown as a percentage.
- A good ACoS is one below your break-even ACoS, which equals your profit margin before ads.
- Use TACoS to see how ads affect total sales, not only ad-attributed sales.
- Lowering ACoS blindly can reduce growth. Set different targets for launch, growth and profit phases.
- Improve listings and conversion rate before cutting bids, because better conversion lowers ACoS for free.
What ACoS means
ACoS stands for Advertising Cost of Sales. It tells you how much you spent on Amazon ads for each unit of sales those ads generated.
ACoS = ad spend ÷ ad sales × 100
If you spend 20 on ads and those ads generate 80 in sales, your ACoS is 25%.
Start with your break-even ACoS
The only useful target is one you can afford. Break-even ACoS equals your profit margin before advertising, as a percentage of the selling price.
Selling price 25. Product cost, Amazon fees and shipping total 15. Margin before ads is 10, which is 40% of the price. Your break-even ACoS is 40%. At 40% ACoS you make no profit on that sale, below it you profit and above it you lose money on the ad-driven sale.
Your numbers will be different, so use your own cost data.
So what is a good ACoS?
A good ACoS is one that fits your goal:
- Launch phase: you may accept an ACoS above break-even to win ranking, reviews and sales history.
- Growth phase: aim near break-even while you scale.
- Profit phase: target well below break-even to protect margin.
Be careful with benchmarks you find online. Margins differ by category and seller, so an average ACoS from another business tells you little about yours.
ACoS vs TACoS vs ROAS
| Metric | Formula | What it tells you |
|---|---|---|
| ACoS | Ad spend / ad sales | Efficiency of the ad-attributed sales |
| TACoS | Ad spend / total sales | How dependent you are on ads overall |
| ROAS | Ad sales / ad spend | Return per unit spent, the inverse of ACoS |
A rising TACoS with flat sales is a warning sign. A falling TACoS while total sales grow suggests that ads are helping organic sales.
How to lower ACoS the right way
- Fix conversion first. Better title, images, bullets, A+ content, price and reviews raise conversion rate, which lowers ACoS.
- Add negative keywords to stop spend on irrelevant search terms.
- Adjust bids by performance. Lower bids on keywords that spend without sales and raise them on those that convert.
- Split campaigns by intent: brand, exact-match winners, discovery and product targeting.
- Review placements and days or times where available.
- Check your price and coupons. A small price change can change conversion more than a bid change.
Common ACoS mistakes
- Chasing a low ACoS and cutting spend so far that sales drop.
- Judging a campaign after only a few days of data.
- Ignoring organic sales when comparing performance.
- Using the same target for every product, even though margins differ.
- Forgetting that returns, taxes and storage fees reduce real profit.
When to get help
If ACoS is above break-even and you are not sure why, an account audit looking at search terms, listing quality and structure is the quickest route to an answer.
Frequently asked questions
What is a good ACoS on Amazon?
A good ACoS is below your break-even ACoS, which is your profit margin before ads. The right figure depends on product costs, fees, price and goals, so general benchmarks are only a rough guide.
How do I calculate ACoS?
Divide advertising spend by ad-attributed sales and multiply by 100. For example, 20 spent on ads that generate 80 in sales gives an ACoS of 25%.
What is break-even ACoS?
It is the ACoS at which an ad-driven sale earns zero profit. It equals your margin before advertising as a percentage of price. Staying below it means each ad sale contributes profit.
What is the difference between ACoS and ROAS?
They are inverses. ACoS is spend divided by ad sales, and ROAS is ad sales divided by spend. A 25% ACoS equals a ROAS of 4.
What is TACoS on Amazon?
TACoS is Total Advertising Cost of Sales, which divides ad spend by total sales, including organic. It helps you see whether ads are growing the business or just replacing organic sales.
Is a high ACoS always bad?
No. During launch you may accept a higher ACoS to gain ranking and reviews. It is a problem when it stays above break-even without a clear plan to improve.
How long should I wait before changing bids?
Give campaigns enough clicks and days to collect meaningful data before judging. Changing bids on tiny samples can lead you to cut keywords that would have converted.
How can I lower my ACoS without losing sales?
Improve listing quality and conversion rate, add negative keywords, reduce bids on non-performing terms and focus budget on proven searches. Avoid slashing budgets across the board.
Where we can help
If you want help bringing ACoS under control, start with these services.
Request an Amazon PPC audit
Share your margins and goals. We will review search terms, structure and listings and show where spend is leaking.
Written by the MAQ Digital Media team. Platform features, policies and interfaces change often, so check each platform’s current help documentation before acting on any step. Last reviewed 1 November 2026.