The main way to measure profitability is by tracking something called return on ad spend, which means looking at how much money you made compared to how much you spent on ads. If you spent 100 dollars and made 400 dollars from sales, your return is good. Marketers also track cost per conversion, which is how much each sale or sign-up cost you. These numbers tell you clearly if the campaign is earning more than it is costing. What metric do you focus on most when judging if a paid search campaign is worth it?