The Return on Investment (ROI) can be aptly measured by website traffic that are eventually converted into new paying customers. This metric will also help you identify which area in your digital marketing campaign is driving sales and revenue, and which areas should be given more room for improvement.
ROI is measured by the number of new paying customers for a given time period. The cost for acquiring these new customers on the other hand is defined by getting the total of your marketing and advertising costs for a particular time period divided by how many new paying customers were generated during that same period. Although calculations may not be that perfect, CAC can give you with good insight on how effective and successful your digital marketing campaigns can be.