GMROI is a key retail metric. A GMROI above 1 means you sell inventory for more than it costs; many retailers aim for 3 or more. It helps decide which products deserve shelf space and which tie up cash.
How to use the GMROI Calculator – Gross Margin Return on Investment
- Starting inventory cost
- Final inventory cost
- Gross profit
Results update as you type, and every field accepts the units shown in its menu.
How it works
Enter the inventory cost at the start and end of the period and the gross profit earned on it.
Tips
- Use figures for the same period (a month, a quarter or a year) for every input so ratios compare like with like.
- Track the metric over time – the trend usually tells you more than a single value.
- Compare your result with industry benchmarks, which vary a lot between sectors.
- Treat the result as a starting point for a decision, then check the assumptions behind each input.
Common mistakes to avoid
- Mixing monthly and yearly numbers in the same calculation.
- Using revenue where the formula needs profit (or the other way round).
- Forgetting hidden costs such as taxes, fees, overheads or your own time.
Inputs explained
| Field | What to enter |
|---|---|
| Starting inventory cost | Amount in your currency |
| Final inventory cost | Amount in your currency |
| Gross profit | Amount in your currency |
What each result means
- Average inventory cost = ([Starting inventory cost] + [Final inventory cost])÷2
- GMROI = [Gross profit]÷[Average inventory cost]
- GMROI as a percentage = [GMROI]×100
Example values
How the main result changes when Starting inventory cost changes and everything else stays at the example values above:
| Starting inventory cost | GMROI (×) |
|---|---|
| 20,000 | 3.86 |
| 30,000 | 3.38 |
| 40,000 | 3 |
| 50,000 | 2.7 |
| 60,000 | 2.45 |
| 80,000 | 2.08 |
Formula
Average inventory cost = (beginning + ending inventory at cost) ÷ 2GMROI = gross profit ÷ average inventory costWorked example
Inputs — Starting inventory cost: $40,000; Final inventory cost: $50,000; Gross profit: $135,000.
Results — Average inventory cost = $45,000.00; GMROI = 3 ×; GMROI as a percentage = 300 %.
Frequently asked questions
What is a good GMROI?
Above 1 means profit; 3 or more is a common retail target.
How do I improve GMROI?
Raise margins, reduce slow-moving stock and turn inventory faster.
Is GMROI the same as inventory turnover?
No – GMROI includes margin, turnover only counts how often stock is sold.
What formula does the GMROI Calculator – Gross Margin Return on Investment use?
Average inventory cost = (beginning + ending inventory at cost) ÷ 2.