Advertising Metrics That Matter: ACoS, TACoS, and ROAS

Advertising throws a lot of numbers at you, but a handful decide whether you're making money. Learn to read those and you can tell a healthy campaign from one that's quietly losing you cash, on either platform.

These three answer the only question that ultimately matters: is the advertising paying for itself?

• ACoS (Amazon). Advertising cost of sale, your ad spend divided by ad sales. An ACoS of 25% means you spent a quarter of your ad revenue on the ads. Below your break-even point it's profit, above it you're paying for sales.
• TACoS (Amazon). Total advertising cost of sale, ad spend against total revenue including organic. A falling TACoS over time usually means your ads are lifting organic rank and the product leans less on paid traffic.
• ROAS (dropshipping and paid social). Return on ad spend, revenue divided by ad spend. A ROAS of 3 means three dollars back for every one spent. It's ACoS turned upside down, and your break-even ROAS comes straight from your margin.

When a campaign underperforms, these tell you why.

• CTR, click-through rate. How often people who see your ad click it. A low CTR points at the creative, the main image, or the title, not the targeting.
• CPC, cost per click. What you pay for each click. Rising CPCs squeeze your margin and often mean more competition or a tired creative.
• Conversion rate. How often a click becomes a sale. If clicks are cheap but few convert, the problem is usually the listing or the product, not the ad.

Every one of these numbers lies when the sample is small. A single day, or a handful of clicks, can look brilliant or disastrous and mean nothing. Wait for enough spend and enough sales before you act, and judge the trend over weeks rather than reacting to the noise of a single afternoon.