Return on marketing investment or ROMI is a metric used in online marketing to measure a marketing campaign's effectiveness. It examines the results concerning the intended marketing objective. ROMI is a subcategory of return on investment (ROI) because the cost is specific to marketing.As a percentage ratio, ROMI demonstrates profitability or waste of an initial sum of money invested. Calculate ROMI with the following formula:ROMI = ((income from marketing – cost of goods – marketing expenditures) / marketing expenditures) * 100.If ROMI is less than 100%, then marketing investments were wasteful. If its more than 100%, they were profitable.For example, we need to understand the effectiveness of an Instagram Ads campaign. Monthly spending was $2,400, and the campaign generated sales of $31,200. Taking into account the cost of goods sold equals $24,960, calculate the effectiveness of the advertising campaign with the formula:ROMI = ((31,200 – 24,960 – 2,400) / 2,400) * 100 = 160%In this case, the ROMI equals 160% for the Instagram Ads campaign. That means that the campaign is profitable. The campaign, therefore, generated $1.60 of income for every dollar spent on marketing.