GMROI Calculator: Gross Margin Return on Inventory Investment
Calculate GMROI, the gross margin earned per $1 of average inventory at cost, from sales, COGS and inventory (average, beginning and ending, or a list of month-end counts), with gross margin, inventory turnover, days on hand, an annualized figure for part-year data, carrying-cost check, target inventory and retailer benchmarks.
How it works
GMROI = gross margin ÷ average inventory at cost · Gross margin = net sales − COGS · Average inventory = (beginning + ending) ÷ 2, or the mean of several counts (13 month-start counts for a year) · GMROI = gross margin % × (sales ÷ average inventory at cost) · Inventory turnover = COGS ÷ average inventory · Days on hand = 365 ÷ turnover · Annualized GMROI = GMROI × 12 ÷ months covered
GMROI (gross margin return on inventory investment) ties profit to the cash locked up in stock: it is the gross margin earned for every dollar of average inventory held at cost. A GMROI of 2.67 means each $1 of inventory produced $2.67 of gross margin over the year. Above 1.0 the inventory earns back more than its cost; a typical retailer is above 3.0, but the right level depends on the category. GMROI is the product of two levers: gross margin percentage and the sales-to-stock ratio (sales ÷ average inventory at cost). A grocer with a 25% margin and fast turnover and a jeweler with a 50% margin and slow turnover can reach the same GMROI by different routes. The scenario table shows how much carrying less stock or raising margin would move it. Use inventory at cost averaged over the same period as the sales. Beginning plus ending divided by 2 is common; the 13-point method (the start of each month plus the last month-end, divided by 13) smooths seasonal swings. GMROI scales with the length of the period, so a month’s figure is about one-twelfth of a year’s; enter the months covered to annualize part-year data. GMROI ignores operating costs, so a line with a GMROI just above 1 may still lose money once storage, staff and the cost of capital are paid; the optional carrying cost gives a rough net figure.
Worked example
A store sells $500,000 a year with $300,000 of COGS, leaving a $200,000 gross margin (40.00%). Against $75,000 of average inventory at cost, GMROI = 200,000 ÷ 75,000 = 2.67: every $1 of inventory returns $2.67 of gross margin. The same answer comes from 40% × the sales-to-stock ratio of 500,000 ÷ 75,000 = 6.667. Inventory turns 300,000 ÷ 75,000 = 4.00 times a year, about 91 days on hand. Holding 20% less inventory ($60,000) for the same margin would lift GMROI to 3.33.
Sources: Shopify Retail: GMROI formula, 13-point average and retailer GMROI from SEC filings · Omni Calculator: GMROI calculator (gross profit ÷ average inventory cost) · Wikipedia: Gross margin return on inventory investment (period effect, 3.0 benchmark)
Frequently asked questions
What is a good GMROI?
Above 1.0 means you earn more gross margin than the inventory investment. A frequently quoted rule of thumb is about 3.0 or more for a typical retailer. Large US retailers range widely: Shopify’s calculations from SEC filings put Abercrombie & Fitch at about 6.1, Ulta Beauty about 2.4 and Best Buy about 1.8. Compare against your own category and your history.
How do you calculate GMROI?
Divide gross margin (sales minus cost of goods sold) by average inventory at cost. With $325,000 of gross margin and $120,000 of average inventory, GMROI = 325,000 ÷ 120,000 = 2.71.
How do I calculate average inventory for GMROI?
At cost, over the same period as the sales. The quick method is (beginning + ending inventory) ÷ 2. For a year, a more accurate method adds the inventory at the start of each of the 12 months plus the final month-end and divides by 13. Paste the counts in list mode to use it.
How is GMROI different from inventory turnover and margin?
Margin ignores how much cash is tied up, and turnover ignores how much you earn on each sale. GMROI combines them: gross margin % × sales ÷ average inventory at cost. A thin-margin product that sells fast can out-earn a high-margin product that sits on the shelf.
Should inventory be valued at cost or retail?
At cost. GMROI compares margin with the money actually invested in the goods. Using retail value would understate the return and make comparisons inconsistent.
Can I calculate GMROI for a month or a quarter?
Yes, but the result is for that period only: $8,000 of margin on $25,000 of inventory in one month is 0.32, which is about 3.84 a year. Enter the months covered under More options to see the annualized figure, or compare like with like.
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Educational estimate, not financial or tax advice.