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ACOS (Advertising Cost of Sales) is the key metric for Amazon sellers. But most calculators require login or paid tools. Here's a free, instant one — no account needed.
ACOS under 25% is excellent for most sellers. Above 35% means you’re spending too much. Use our FBA Profit Calculator to see your true margin.
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For most categories a ACOS under 25% is strong, 25–35% is workable if your margins are healthy, and anything above 35% usually means advertising is eating the profit. The real ceiling is your break-even ACOS — the pre-advertising margin on the product — not an industry average.
ACOS = (ad spend ÷ ad sales) × 100. If you spend $50 in ads to generate $200 in ad-attributed sales, your ACOS is 25%. Enter both figures in the calculator above and you get the number instantly — no login, no cost.
Break-even ACOS equals your profit margin before advertising. If a unit nets $8 on a $40 sale (a 20% margin), any ACOS above 20% loses money on that ad-driven sale. Get the margin right first with our FBA Profit Calculator.
ACOS compares ad spend with ad-attributed sales only, so it measures advertising efficiency in isolation. TACOS (total ACOS) compares ad spend with total sales including organic, showing how much of the whole business advertising is funding. TACOS falls as organic ranking improves even when ACOS stays flat.
They are two views of the same number. ROAS = ad sales ÷ ad spend, so an ACOS of 25% is exactly a ROAS of 4.0. Amazon reports ACOS in Seller Central; ROAS is the convention on Google and Meta ads. Use whichever your team reasons in faster.
Start with wasted spend, not bids: add negative keywords, split exact-match winners into their own campaign, lower bids on search terms that get clicks but no orders, and lift conversion rate with better images, bullets and A+ content so the same clicks produce more sales. Our Negative Keywords Guide walks through the cleanup step by step.
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