GMROI: How to Calculate Gross Margin Return on Inventory

GMROI (gross margin return on inventory investment) measures how much gross profit a retailer earns for each dollar invested in average inventory. It combines margin and inventory efficiency into one metric.

GMROI formula

GMROI = Gross Profit ÷ Average Inventory Cost

If annual gross profit is $240,000 and average inventory is $120,000:

GMROI = $240,000 ÷ $120,000 = 2.0

The business generated $2 of gross profit for every $1 invested in average inventory.

How to calculate gross profit

Gross Profit = Net Sales − Cost of Goods Sold

Use net sales after discounts and returns where appropriate.

How to calculate average inventory

Average Inventory = (Beginning Inventory + Ending Inventory) ÷ 2

For seasonal businesses, use monthly or weekly balances to avoid distortion.

Why GMROI matters

A product can have a high margin but still use inventory poorly if it sells slowly. Another product can have a lower margin but produce more gross profit because it turns quickly.

GMROI helps compare those situations.

GMROI vs gross margin

• Gross margin measures profit relative to sales.
• GMROI measures gross profit relative to inventory investment.

Use both.

GMROI vs inventory turnover

Turnover measures inventory velocity. GMROI adds profitability.

A useful relationship is:

GMROI ≈ Gross Margin % × Inventory Turnover

when the measures are calculated consistently.

Example: two products

Product A:

• Gross profit: $20,000
• Average inventory: $20,000
• GMROI: 1.0

Product B:

• Gross profit: $18,000
• Average inventory: $6,000
• GMROI: 3.0

Product B produces less total gross profit but uses inventory investment much more efficiently.

What is a good GMROI?

There is no universal benchmark. GMROI varies by category, margins, seasonality and business model.

Current 2026 retail examples published by Shopify range materially across categories, which is why internal trend and category comparison are more useful than one generic target.

How to improve GMROI

Increase margin

Improve pricing, supplier cost, or discount discipline.

Increase turnover

Reduce slow-moving stock and buy closer to demand.

Reduce excess inventory

Lower average inventory without creating stockouts.

Improve assortment

Allocate more inventory to products that combine margin with healthy sell-through.

Transfer stock

Move inventory to locations where it can sell faster.

GMROI by SKU, category and location

Companywide GMROI can hide weak categories. Calculate it by SKU, department, location or supplier where the data is reliable.

GMROI limitations

• depends on accurate cost data
• can be distorted by seasonality
• does not capture strategic or traffic-driving products
• should not be used alone for assortment decisions

How Stash helps

Stash connects inventory, product performance, suppliers, purchasing and location data so teams can evaluate profitability alongside inventory investment.

Frequently asked questions

What does GMROI of 2 mean?

It means $2 of gross profit is generated for every $1 invested in average inventory.

Is higher GMROI always better?

Usually it indicates more efficient inventory use, but context matters. Extremely low inventory can increase stockout risk.

Should GMROI use retail value or cost?

Average inventory is typically measured at cost so it aligns with gross profit and COGS.

Next steps

Calculate GMROI by category and compare it with turnover, sell-through and product margin.

GMROI by category example

Assume a retailer has three categories:

Category	Gross profit	Average inventory	GMROI
Accessories	$90,000	$30,000	3.0
Footwear	$120,000	$60,000	2.0
Outerwear	$100,000	$100,000	1.0

This does not automatically mean the retailer should eliminate outerwear. It means the category needs investigation: slower turns, seasonal inventory, excessive depth, or weaker margins may be lowering inventory productivity.

How seasonality can distort GMROI

A snapshot taken immediately after a large seasonal buy can temporarily depress GMROI because average inventory rises before the sales season occurs. Compare similar periods year over year and use monthly average inventory when seasonality is strong.

How to use GMROI in assortment decisions

Use GMROI as a filter, not an automatic deletion rule. Products can play strategic roles such as driving traffic, completing an assortment, supporting attachment sales, or serving key customers. Review GMROI alongside gross profit dollars, sell-through, stockouts, return rate and shelf-space requirements.