What Is a Good ACOS on Amazon?

Here is the honest answer: there is no universal good ACOS. A 15% ACOS can be terrible for one product and a missed opportunity on another. The right number comes from your unit economics, not a figure someone heard on a podcast. This guide shows you how to calculate the ACOS that's actually good for your business.

What ACOS Is (and What a Good ACOS Really Means)

ACOS (Advertising Cost of Sales) is simply your ad spend divided by the revenue those ads generated. Spend $20 to make $100 in ad sales, that's a 20% ACOS. It's Amazon's own metric, defined in their official advertising glossary.

That's all it is: a ratio. It is not a health score. A low ACOS isn't automatically good and a high ACOS isn't automatically bad, because ACOS says nothing about what's left after Amazon's fees, your cost of goods, and returns. The number only becomes meaningful once you know what each product can actually afford.

Why there's no single good ACOS

Take a brand selling two products. A small $25 accessory and a $75 bundle. Same brand, same account, completely different economics.

The $25 accessory: cost of goods ~$6, Amazon fees ~$8, refunds ~8%, for a contribution margin before ads of ~$11.

The $75 bundle: cost of goods ~$28, Amazon fees ~$24, refunds ~12%, for a contribution margin before ads of ~$23.

The accessory keeps a much larger share of its price after costs, so it can afford to spend far more on advertising before it stops being profitable. Force both products to a single 15% ACOS target and you under-advertise the one that could scale aggressively, while risking the other.

How to calculate YOUR break-even ACOS

Break-even ACOS answers one question: what percentage of revenue can I spend on ads before profit hits zero? It's your contribution margin as a percentage of price.

Using the two products above: the $25 accessory has ~$11 margin on $25, for a ~44% break-even ACOS. The $75 bundle has ~$23 margin on $75, for a ~30% break-even ACOS.

So a 40% ACOS that looks alarming on the accessory is actually still profitable and helping it grow category position. And a safe-looking 25% ACOS on the bundle is much closer to its limit than the dashboard suggests. Your good ACOS sits below your break-even, by however much profit you want to keep.

ACOS vs TACOS, the number most sellers miss

ACOS only looks at advertising sales. TACOS (Total Advertising Cost of Sales) measures ad spend against total revenue, ads plus organic. That's the one that tells you whether advertising is actually growing the business.

Here's the relationship: if your TACOS target is around 10% and ads drive about half your sales, your ACOS can sit near 20% and the account is perfectly healthy. Looking at ACOS alone, without that context, is misleading.

The simplest way to hold both in your head: ACOS tells you how your campaigns are performing. TACOS tells you how your business is performing.

The trap: a good ACOS while you lose money

We audited a $2.1M/year skincare brand whose numbers looked healthy: ACOS around 31%, TACOS around 18%, clean listings, solid reviews. But margins that should have been 35% were coming in near 12%. They were losing money on paid traffic every week.

The ACOS looked fine because the number looked fine. What it hid: spend going to late-night research-mode shoppers who converted badly and often bought from competitors, and a flat target applied across products that should have been treated completely differently.

That's the danger of chasing a magic ACOS. The dashboard can look great while the bank account doesn't.

So what's a good ACOS for you?

Not every product should be optimized the same way. Once you know each product's break-even ACOS, you can give it a role. Growth products can run close to break-even ACOS to capture demand and category position. Rank products spend to win and hold a key keyword position. Profit products run well below break-even to generate consistent margin.

A good ACOS isn't one number, it's a target per product, set from real economics and the job that product is doing. Set it that way and the conversation finally matches your profitability instead of a number you heard somewhere.

Common Questions

What is a good ACOS on Amazon?

There's no universal number. A good ACOS is one that sits below your break-even ACOS (your contribution margin as a percentage of price) by enough to hit your profit goal. For a high-margin product that might be 35-40%; for a thin-margin product it might be under 15%. Calculate it from your cost of goods, Amazon fees, and refund rate, not a generic benchmark.

What is the difference between ACOS and TACOS?

ACOS measures ad spend against ad-attributed sales. TACOS measures ad spend against total sales (ads plus organic). ACOS tells you how campaigns perform; TACOS tells you how the business performs. A healthy account often shows a higher ACOS with a low, stable TACOS.

How do I calculate break-even ACOS?

Take your price, subtract cost of goods, Amazon fees, and average refund cost to get contribution margin. Divide that margin by the price. A $25 product with ~$11 left over has a ~44% break-even ACOS, the point where ad profit reaches zero.

Is a 15% ACOS good?

Sometimes, often not. 15% might leave a high-margin product badly under-advertised, or it might already be unprofitable for a thin-margin product. The number means nothing without your unit economics behind it.

What is a bad ACOS?

Any ACOS above your break-even point on a product you're trying to run for profit, or a low ACOS that's quietly starving a product that could scale. Bad is about the gap between your ACOS and what the product can actually afford, not a fixed threshold.