What is a good Advertising Cost of Sale (ACoS)? It goes on beyond ad spend divided by total sales. ACoS depends on a number of factors: goal, proper campaign structure, product life cycle, profit margins and so on. A low ACoS is a good thing, but what you determine as low will vary by product. We will unpack our holistic approach to ACoS to help you find the sweet spot when balancing your sponsored ad spend and product margins.