ROI stands for return on investment. If you Google “marketing ROI,” you’ll get a million different defintions. Which you use depends on your needs and business situation. The most simplistic version is to take the gross profit generated from a particular marketing investment, subtract the cost of the marketing campaign from it and divide this number by the cost of the marketing. ROI is typically expressed as a percentage, so multiple your answer by 100. So, if you spend $1,000 on a marketing campaign that generates $5,000 in gross profit, your ROI would be 400%.