Break-even ACoS is the highest advertising cost of sale you can run before an ad-driven order stops making money. It equals your profit margin before advertising. Put your price and costs in below and this calculator gives you the break-even ACoS figure, plus a target range for profit, growth and defence.
What is ACoS?
ACoS (advertising cost of sales) is ad spend divided by the sales those ads generated, shown as a percentage. Amazon Ads defines it as “ACOS = (ad spend ÷ ad revenue) x 100”. Spend £30 to get £100 of attributed sales and your ACoS is 30%. Its inverse is ROAS: £100 ÷ £30 = 3.33.
ACoS alone doesn’t tell you if that’s good. 30% is profitable on a product with a 40% pre-ad margin and a loss on one with 25%.
How do you calculate break-even ACoS?
Break-even ACoS = pre-ad profit ÷ selling price (ex VAT). Pre-ad profit is what one unit leaves you after product cost, shipping to Amazon and all Amazon fees, but before advertising. Amazon’s own guide says the same thing in plain words: break-even ACoS is “directly linked to your profit margin”, and your ACoS “needs to be lower than your profit margin” to stay profitable.
The costs people forget are storage, returns, refund administration and the digital services fee. Our break-even ACoS guide walks through all of them. If you’d rather build pre-ad profit line by line, the Amazon profit calculator outputs it for you.
Which price should you use: ex VAT or inc VAT?
Use the ex-VAT price for your true break-even, but check which basis your ad sales figure uses before you compare. This is the UK-specific trap.
As of September 2026, Amazon’s help pages don’t say whether the attributed sales in Campaign Manager include VAT. Sellers on Amazon’s own forums have asked and got no official answer. Check it yourself: compare a day’s attributed sales for one ASIN with the VAT-inclusive order values in your order report. If they match, the ACoS you see in the console is lower than your real ACoS by a factor of 1.2.
So a VAT-registered seller needs two numbers:
| Figure | Formula | Use it for |
|---|---|---|
| True break-even | Pre-ad profit ÷ price ex VAT | Your P&L, your pricing |
| Console-basis break-even | Pre-ad profit ÷ price inc VAT | Comparing against ACoS in Campaign Manager |
If you aren’t VAT registered, there’s no VAT in the price and the two are the same.
Worked example (illustrative)
A made-up product, not client data. £24.99 inc VAT, VAT registered. COGS and inbound £6.10, referral fee 15% (£3.75), FBA fee £3.20, storage and digital services fee £0.29, returns allowance £0.40.
| Line | Amount |
|---|---|
| Net price (ex VAT) | £20.83 |
| COGS + inbound | −£6.10 |
| Amazon fees | −£7.24 |
| Returns allowance | −£0.40 |
| Pre-ad profit | £7.09 |
| True break-even | 34.0% |
| Console-basis break-even | 28.4% |
If this seller watched the console and treated 34% as the ceiling, every campaign between 28.4% and 34% would look fine and lose money. On £10,000 of ad sales a month, running at a 32% console ACoS means about £360 a month lost, not banked.
What should your target ACoS be?
Your target ACoS is break-even minus the margin you want to keep, set by what the campaign is for. Amazon doesn’t publish a recommended figure; its guide says each brand “will have a different target ACOS”. The bands below are our working heuristics, not Amazon rules.
| Campaign goal | Target ACoS (heuristic) | On a 28.4% console break-even |
|---|---|---|
| Profit | 10–15 points below break-even | 13–18% |
| Defend rank on proven terms | At break-even | ~28% |
| Launch or rank push | Break-even to +5 points, time-boxed | 28–33% |
| Clear stock | Above break-even, below full unit cost | Case by case |
Above break-even, you’re buying rank or data instead of profit. Fine if deliberate and time-boxed. The account-level view of whether that spend is paying off is TACoS, not ACoS.
How to read the result
These readings are heuristics from our own account work:
- Break-even under 15%: ads will struggle to pay on this product at this price. Look at price, COGS or size tier before you look at bids.
- 15–30%: a common range for private-label products. Exact-match and defensive campaigns can run profitably.
- 30%+: you have room to fund discovery and launch spend. Don’t let that room turn into waste.
Recalculate whenever a fee, price or landed cost changes. The 2026 fee changes moved break-even for many UK products this year.
FAQ
What is break-even ACoS?
The ACoS at which an ad-driven sale makes zero profit. It equals your profit margin before advertising: pre-ad profit divided by selling price. Run below it and advertised orders make money; run above it and each one loses money, before counting any organic lift.
What is a good ACoS on Amazon?
There’s no universal number. Amazon says each brand will have a different target. A good ACoS is one below your break-even, with the gap set by your goal. As a heuristic, we aim 10–15 points under break-even on profit campaigns.
How is ACoS calculated?
Amazon Ads calculates it as ad spend divided by ad-attributed sales, multiplied by 100. £250 of spend that produced £1,000 of attributed sales gives a 25% ACoS. It only counts sales Amazon attributes to ads, not your total sales.
Is break-even ACoS the same as target ACoS?
No. Break-even is where you stop making money. Target ACoS is where you choose to run, usually below break-even for profit or at it for defence. Launch campaigns sometimes run above break-even for a set period.
Does ACoS include VAT for UK sellers?
Amazon doesn’t document it either way. Compare attributed sales with VAT-inclusive order values in your order report. If they match, divide your ex-VAT break-even by 1.2 before comparing it with console ACoS. Check against your own order report.
What’s the difference between ACoS and TACoS?
ACoS divides ad spend by ad-attributed sales. TACoS divides ad spend by total sales, including organic. ACoS judges campaigns; TACoS shows whether ads are growing the whole business. Use our TACoS calculator for the account view.
Sami Sultan runs Ecom Enable, an Amazon growth partner for DTC brands. ACoS definition and fee rates checked 22 September 2026. Want your break-even compared with what your campaigns are actually running at? That’s part of our free Amazon audit, or see our advertising service.
Sources: Amazon Ads: What is ACOS?; Amazon UK: referral fees; About Amazon EU: 2026 European fee update; Seller Central forum: is ACOS based on sales incl. or excl. VAT?; Armstrong Watson: VAT on Amazon fees from August 2024.