A campaign that costs €1,000 and generates €3,000 in gross profit has an ROI of 200%. ROI differs from return on ad spend, or ROAS, which divides revenue by ad spend alone and ignores product costs, fees and time. A campaign can show a healthy ROAS and still lose money once those costs are counted.
Measuring marketing ROI honestly is harder than the formula suggests. Results arrive over months, customers come back to buy again, and much of the value of content and brand-building never shows up as a tracked sale. A sensible approach is to calculate ROI where it can be measured, such as a direct response campaign, and to judge longer-term work against leading indicators rather than forcing a number on it.