Evaluating Capital Productivity with GMROI
GMROI formula and worked example
GMROI = (Net Sales − Cost of Goods Sold) ÷ Average Inventory at Cost
First subtract cost of goods sold (COGS) from net sales to get gross margin. Average inventory at cost is (beginning inventory at cost + ending inventory at cost) ÷ 2. For example, net sales of $120,000, COGS of $80,000, beginning inventory of $18,000 and ending inventory of $22,000 give $40,000 gross margin ÷ $20,000 average inventory = 2.0 GMROI. Use the same period and currency for every input. GMROI is a ratio, not a percentage or net profit.
The two levers: Margin vs. Velocity
Retailers can achieve an identical GMROI of 2.0 through two distinct strategies: a high-margin, slow-turning specialty item (e.g. 50% margin turning twice a year), or a low-margin, fast-turning staple (e.g. 20% margin turning eight times a year). Understanding which lever drives a category prevents counterproductive markdowns or unnecessary over-ordering.
Practical limitations of GMROI
GMROI evaluates gross margin, not net operating profit. It does not account for store labor, handling costs, physical shelf space, or utilities. A high-GMROI product that requires intensive customer service or bulky refrigeration may produce less net profit than a lower-GMROI shelf staple.