GMROI, or gross margin return on inventory investment, compares gross profit dollars with average inventory held at cost over a defined period. It asks how much gross profit the business generated relative to its average inventory investment.
For a retail buyer, GMROI can help review assortment and inventory levels alongside availability and margin. It is not net profit, cash return or proof that an individual order should be increased or cut.
GMROI formula
GMROI = gross profit for the period / average inventory at cost
Gross profit = net revenue − COGS
A GMROI of 2.4 means $2.40 of gross profit per $1 of average inventory cost during the stated period. It does not mean a 240% net return after operating expenses.
A ratio below one means gross profit was less than average inventory value. Inventory value is a balance, not the expense of holding stock, so that comparison alone does not establish an operating loss. Likewise, a high GMROI does not establish that overhead, financing and taxes were covered.
Keep the period and scope consistent
Use gross profit and average inventory for the same category, locations and period. Annual and quarterly GMROI are not directly comparable without explaining the time basis. Do not casually annualize a seasonal quarter as though its performance repeats four times.
A simple average is opening inventory plus closing inventory divided by two. If balances vary materially, use a consistent series of snapshots or a time-weighted method that captures the change. A holiday stock build can disappear from an opening-and-closing average.