Inventory turnover measures how many times you sell and replace your inventory over a given period. It is one of the clearest indicators of how efficiently a business manages its stock, and it has direct implications for cash flow, storage costs, and profitability.
The Formula
Inventory turnover = Cost of goods sold ÷ Average inventory
Average inventory is typically the average of beginning and ending inventory for the period:
Average inventory = (Beginning inventory + Ending inventory) ÷ 2
Example: a business with $240,000 in annual COGS and average inventory of $60,000:
$240,000 ÷ $60,000 = 4.0 inventory turns per year
This means the business sells and replaces its entire inventory roughly every three months (once per quarter).
Days Sales of Inventory (DSI)
A companion metric expresses the same information in days:
DSI = 365 ÷ Inventory turnover
At 4.0 turns per year:
DSI = 365 ÷ 4.0 = 91 days
DSI answers: "If I stop buying inventory today, how many days until I sell through what I have?" Lower DSI means inventory moves faster.
What Is a Good Inventory Turnover Ratio?
The right number depends heavily on your industry:
- Grocery and fresh food: 12–30+ (high perishability, low margins)
- Consumer electronics: 5–10
- Apparel / fashion: 4–6
- Furniture: 2–4
- Jewelry: 1–3
- Luxury goods: 1–2
There is no universal "good" ratio. A ratio that is high for your industry suggests efficient inventory management; a ratio that is low may indicate overstocking, slow-moving products, or forecasting problems.
Why Inventory Turnover Matters
Cash flow: Inventory sitting on shelves is cash that is not in your bank account. Faster turnover means you convert inventory to cash more quickly, reducing the working capital required to run the business.
Storage costs: Warehousing, insurance, and handling cost money. Inventory that turns slowly accumulates these costs without generating proportional revenue.
Obsolescence risk: Products that sit too long risk becoming outdated, going out of season, or expiring. Electronics, fashion, and perishables are especially vulnerable.
Margin pressure: To move slow-turning inventory, businesses often discount. Discounting compresses margin, so the slow inventory ends up costing more than its carrying cost alone.
When High Turnover Can Be a Problem
Very high inventory turnover is usually good, but it can indicate stockouts, which means you are running out of inventory and potentially turning away customers. If you are frequently unable to fulfill orders due to out-of-stock situations, your turnover may be high for the wrong reason.
The goal is the highest turnover ratio that does not result in stockouts or unacceptably long customer wait times.
Improving Inventory Turnover
- Demand forecasting: Better forecasting reduces both overstock and understock situations
- SKU rationalization: Reducing the number of slow-moving product variants concentrates sales on your best performers
- Pricing and promotions: Clearing slow-moving stock through targeted discounts before it ages further
- Supplier lead time reduction: Shorter lead times allow you to order closer to demand, reducing the safety stock you need to carry
- Just-in-time purchasing: Ordering more frequently in smaller quantities increases turnover but may reduce per-unit purchase discounts