Your ACoS of 25% sits below your 30% break-even ACoS, so each advertised sale still turns a profit. Your TACoS of 10% shows ad spend against the whole business; if it falls over time, your organic sales are growing.
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ACoS, short for Advertising Cost of Sales, is how much you spent on ads divided by the sales those ads produced. The formula is ad spend divided by ad sales, times 100. Spend $500 on Amazon ads that return $2,000 in sales and your ACoS is 25%, meaning it cost 25 cents in advertising to earn each dollar of ad revenue. The calculator above runs this math, plus TACoS, ROAS and break-even ACoS, from your own numbers.
ACoS is the headline efficiency metric for Amazon Sponsored Products and most other marketplace ad platforms. A lower ACoS means your ads are working harder: less spend per dollar of sales. It is the mirror image of ROAS, return on ad spend. ROAS is ad sales divided by ad spend, so a 25% ACoS is the same as a 4x ROAS. Sellers reach for ACoS when they want a cost ceiling to bid against, and for ROAS when they want a revenue multiple. Both describe the same campaign from opposite sides, and the calculator shows you each so you can speak to either.
ACoS only sees the sales your ads directly drove. TACoS, Total Advertising Cost of Sales, divides the same ad spend by your total revenue, including organic and repeat sales that no ad touched. That one change in the denominator tells a very different story. A campaign can post a high ACoS yet a low TACoS because most of your revenue now comes from organic rankings and returning buyers. ACoS judges the campaign in isolation; TACoS judges how much your whole business leans on paid ads. Watch them together: ACoS keeps your bidding honest, while TACoS shows whether your brand is building its own demand.
There is no universal "good" ACoS, only one that fits your margins. The deciding line is your break-even ACoS, which equals your profit margin. If you keep 30 cents of profit on every dollar before ad cost, your break-even ACoS is 30%. Run ads at a 20% ACoS and you bank the 10-point gap as profit; run them at 35% and each advertised sale loses money. Many sellers target an ACoS well under their margin on profitable terms and accept a higher one on launch or defensive campaigns. The honest test is simple: compare your ACoS to your break-even ACoS, and watch your TACoS trend downward over time as organic sales grow. If you want that organic base built deliberately rather than left to chance, request a free SEO audit and we will map it for you.
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