I mentioned the other week that I spent a lot of my brand side years explaining
By Antfinch · November 3, 2026 · Curated by George's Blog
I mentioned the other week that I spent a lot of my brand side years explaining ROAS to finance directors.
With hindsight, I was probably bringing the wrong number to the room.
ROAS isn't wrong. It tells you how hard each pound of ad spend is working on the sales the ads take credit for. The trouble is finance don't really care about the sales the ads take credit for. They care about the total.
That's where TACoS is a much easier conversation.. total ad spend as a % of total sales.
But if you're a vendor, there's a catch. The sales Amazon shows you are its own sales, at its retail price. That's not your revenue. Your revenue is what you invoice Amazon, and that's a fair bit lower once their margin comes off.
So work it back. Ad spend as a % of invoiced sales. It'll look worse than the version Amazon shows you (sorry), but it's the one that sits honestly next to every other cost line in your P&L.
If that number's drifting down while sales go up, the ads are helping build something. If it's creeping up every month, you're basically renting your sales.
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