Amazon ACOS Calculator
Ad cost of sale against your break-even.
Amazon revises fee schedules at least annually and adds new surcharges more often. These defaults are a starting point — the figures in your own fee preview are the ones that describe your ASINs.
ACOS
25%
4.00× return on ad spend
At 25% against a 32% break-even you are profitable on advertised sales with 7% of headroom. That headroom is worth spending if it buys rank — ACOS below break-even and volume flat usually means you are underbidding.
How the Amazon ACOS Calculator works
ACOS is ad spend divided by attributed sales. On its own the number means nothing — it only becomes useful against your break-even ACOS, which is simply your margin before advertising. Above that line every advertised sale loses 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 a good ACOS?
Anything below your break-even, which is your margin before advertising. A 40% ACOS is excellent on a 50% margin product and ruinous on a 30% one — there is no universal good number.
How does ACOS relate to ROAS?
They are reciprocals. A 25% ACOS is a 4× ROAS. ACOS is more common on Amazon, ROAS elsewhere; the information is identical.
Should ACOS always be low?
No. Low ACOS with flat volume usually means underbidding — you are winning only the cheapest, easiest clicks and leaving rank on the table. During a launch, deliberately running above break-even to buy velocity is a normal strategy.
Why does ACOS understate advertising cost?
Because it only counts sales the ad was credited with. Spend that lifted organic rank shows up nowhere in ACOS, which is why TACOS exists.