# GMROI calculator for retail inventory

Measure how many dollars of gross margin a line earned for each dollar of average inventory held at cost over the same period. GMROI connects profit with the working capital needed to earn it.

Formula: GMROI = gross margin earned ÷ average inventory at cost.

Example: Gross margin earned 12000; Average inventory at cost 4000.
Result: GMROI 3.00.

## How to calculate it

1. Choose a period and calculate gross margin dollars earned in that period: sales less cost of goods sold.
2. Find average inventory value at cost across that same period, using consistent stock snapshots where possible.
3. Divide gross margin dollars by average inventory at cost. Compare like periods and similar category roles before drawing a conclusion.

## Equal margin, different stock investment

Two homewares lines each earn $12,000 gross margin in a year. Line A carries $4,000 average inventory at cost, giving GMROI 3.0. Line B carries $12,000, giving GMROI 1.0. Line A earns $3 margin per $1 tied up in stock; Line B earns $1.

Line B deserves a closer look before anyone proposes delisting it. Check its shopper role, availability, stock cover, supplier terms and whether reducing the buy would keep the line on shelf when needed.

## Check before acting

- Use gross margin dollars and inventory at cost, both from the same time period.
- A high GMROI can reflect too little stock and missed sales. Review availability alongside the ratio.

## Questions

### What does a GMROI of 3 mean?

The line earned $3 of gross margin for each $1 of average inventory held at cost during the chosen period.

### Can I calculate GMROI in Excel or Google Sheets?

Yes. Divide gross margin dollars by average inventory at cost in a spreadsheet cell. The downloadable workbook and CSV template provide example columns and formulas you can extend for more products.

### Is a higher GMROI always better?

It shows a stronger return on stock investment, but a very lean stock position can cause lost sales. Compare availability and the line's category role too.

### Can I compare GMROI across categories?

Only with care, because margin structures and stock turns vary widely between categories. Comparisons within a similar format and period are usually more useful than one universal threshold.

[Use the interactive calculator](https://twelfth.ai/tools/gmroi).
[Download the gmroi CSV template](https://twelfth.ai/resources/retail-csv/gmroi.csv).
[Download the eight-tab workbook](https://twelfth.ai/resources/retail-metrics-template.xlsx).
[Read the gmroi glossary definition](https://twelfth.ai/glossary/gmroi).
Related calculators: [Sell-through calculator](https://twelfth.ai/tools/sell-through), [Weeks of cover calculator](https://twelfth.ai/tools/weeks-of-cover).
Source: https://twelfth.ai/tools/gmroi