- ACoS (Advertising Cost of Sales)
- Amazon ad spend divided by the revenue those ads generated, shown as a percentage — a measure of how efficient a campaign or keyword is.
The ACoS formula
ACoS = ad spend ÷ ad-attributed revenue × 100. If you spend £250 on a campaign that produces £1,000 of sales, your ACoS is 25%.
What counts as a good ACoS?
There's no universal number. The reference point that matters is your break-even ACoS, which equals your profit margin — the ACoS at which an ad-driven sale makes zero profit. Below it, ads are profitable in isolation; above it, that sale loses money on paper.
The common mistake is treating a low ACoS as the only goal. During a launch, a high ACoS is often correct because you're buying rank and reviews you'll harvest later. That's why experienced sellers manage to TACoS as well as ACoS, and why a low ACoS can quietly cap growth.
Related
Frequently asked questions
Is a lower ACoS always better?
No. A lower ACoS only means a campaign is more efficient in isolation. Cutting spend to lower ACoS often defunds the campaigns that build organic rank, shrinking total revenue while the metric looks better. Judge ACoS against your break-even point and your stage, not in absolute terms.
What's the difference between ACoS and TACoS?
ACoS uses only ad-attributed revenue; TACoS uses total revenue including organic. ACoS measures campaign efficiency; TACoS measures how dependent the whole business is on ads. A falling TACoS means advertising is successfully building organic sales.
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