Amazon ACoS Calculator

Formula + 2-step worked example

Step 1 — grab the two numbers

Take your ad spend and your ad-attributed sales for the same period. In Seller Central's Campaign Manager, both are right there in the Spend and Sales columns.

Step 2 — divide, then multiply by 100

ACoS = (ad spend ÷ ad-attributed sales) × 100. Spend $800 to generate $3,200 in ad sales: 800 ÷ 3,200 = 0.25 → 25% ACoS .

What it tells you. A 25% ACoS means every $1 of ad sales cost 25¢ in ad spend. For the full margin-based framework — including break-even ACoS and how to set a target — see our complete ACoS guide .

Illustrative example — not live Amazon data

Checking last week’s numbers in ten seconds

Scenario. A seller wants a quick read on last week before the Monday bid review.

Inputs. Ad spend $1,200, attributed ad sales $4,800, total sales $12,000.

What the output means. ACoS 25% (spend ÷ ad sales), ROAS 4.0 — the same number in the language your reports use. Reverse mode answers the planning question too: to hit 20% ACoS on $500 of spend you’d need $2,500 in ad sales. Each run is saved to a private on-device history strip so the trend is visible week to week.

Concrete next action. Compare 25% against your own profit margin — ACoS below margin means the ads themselves are profitable. If it’s above, trim bids or harvest negatives before spending more; if below, that’s your signal to scale.

High vs. low — it depends on your margin

Against your break-even margin. If your net unit margin is 40%, a 25% ACoS leaves 15 points of profit — the ads are working. The same 25% on a product with 20% margins loses money. "High" and "low" only make sense next to your own break-even; our ACoS / TACoS calculator with break-even ACoS folds your margin into the verdict. A high ACoS on a brand-new campaign usually just means "gathering data" — judge launches by TACoS trending down, not by one week's ACoS.

Honest limitations. This calculator reads one period at a time and only knows ad-attributed sales, so it can't compute true profitability; add total sales for the TACoS view. And it knows nothing about your costs — the profit verdict only appears if you enter your break-even margin.