To track customer acquisition cost by channel, divide total spend on that channel, including ad spend, platform fees, and tool costs, by the number of new customers it generated in the same period, calculated separately for each channel rather than blended across your whole store. Most founders calculate one blended CAC number and miss that their cheapest-looking channel is often the most expensive once fully loaded costs are included.

A channel that costs $22 per acquisition by ad spend alone can cost $38 once you add in the platform's transaction fees, app subscription, and the labor hours to manage it. Blended CAC hides this completely.