ACOS Calculator
Ad cost of sale, against break-even.
ACOS
28.57%
3.50× ROAS, break-even 42%
Profitable with 13.43% of headroom. Whether to use it depends on whether the extra spend buys rank or just buys more expensive clicks.
How the ACOS Calculator works
ACOS is spend divided by attributed revenue, and it only means something against break-even ACOS — which is simply your contribution margin. Below the line every advertised sale profits; above it, every advertised sale costs you money.
Not financial advice. Marketplace fees change, and they vary by country, plan and seller status. Every rate here is an editable default, not a quoted price — check the platform's current fee schedule before you price a product against it. This is not tax or business advice.
Frequently asked questions
What is ACOS?
Advertising cost of sale: ad spend as a percentage of the revenue it produced. A £4,000 spend generating £14,000 is a 28.6% ACOS.
What is a good ACOS?
Below your contribution margin. At 42% contribution, a 28% ACOS is healthy and a 50% ACOS loses money — there is no universal good figure.
Is a low ACOS always better?
No. A very low ACOS with flat sales usually means underbidding — you are winning only the cheapest, easiest impressions and leaving profitable volume unbought.
Why does ACOS understate advertising's effect?
Because it only counts sales the ad was credited with. Spend that improved organic rank appears nowhere, which is what TACOS exists to capture.