A simple payback-period model for judging channel performance fairly

This planning tool works from four inputs: customer acquisition cost by channel, average order or contract value, gross margin, and, for subscription or repeat-purchase businesses, expected customer lifetime or repeat purchase rate.

From those inputs, it calculates how many days or months it takes for a channel's acquisition cost to be recovered in margin — the payback period — which is a far more decision-useful number than a blended return-on-ad-spend figure, because it accounts for margin and time, not just revenue.

Use it at the channel level, and where volume allows, at the campaign or audience segment level. A channel with a longer payback period isn't automatically a bad channel — it may still be worth funding if the eventual lifetime value is high enough — but it does need a longer patience horizon and a clear cash flow conversation before scaling.