Inventory Turnover Ratio Explained: The Metric That Frees Up Cash (2026)

Inventory turnover is cost of goods sold divided by average inventory, and it counts how many times a business sells through and replaces its entire stock in a year. A ratio of 8 means average inventory turned over eight times, so each item sat roughly 46 days before selling. The ratio matters because inventory is cash in a different shape: every extra turn per year releases working capital that was sitting on a shelf, and every lost turn buries it again.

The Formula and Which Numbers Go In It

Inventory Turnover = Cost of Goods Sold ÷ Average Inventory, where average inventory is (beginning + ending) ÷ 2 for the period. Use COGS, not revenue: revenue includes your margin, so a high-margin business would look artificially efficient if you used the top line. The COGS figure to use is the one you already compute for tax — the IRS sets out the build-up on Form 1125-A, beginning inventory plus purchases plus labor and other costs, less ending inventory — which keeps the ratio reconciled to a filed return.

• Average inventory of two points is a compromise. If your business is seasonal, average the twelve month-end balances instead, or the ratio will be distorted by whichever month you picked.
• Value inventory consistently. FIFO and LIFO produce different ending balances from identical physical stock, so a change in method creates a change in ratio that is purely accounting.
• Exclude consignment stock you do not own and include stock in transit that you do.
• Strip out obsolete inventory you have already written down, or it will drag the ratio while contributing nothing sellable.

Days in Inventory: The Operationally Useful Version

Days in Inventory = 365 ÷ turnover ratio. A ratio of 8 becomes 46 days; a ratio of 4 becomes 91 days. Days is the number to run operations on, because it is directly comparable to your supplier lead time. If stock sits 91 days and your lead time is 21 days, you are holding more than four lead times of cover, which is where excess almost always hides.

What One Extra Turn Is Worth in Cash

The reason to care about the ratio is the balance sheet, not the report. Going from 4 turns to 6 on the same COGS cuts average inventory by a third, and that difference is cash that stops being stock. Add the holding cost you no longer pay — warehousing, insurance, shrinkage, obsolescence, and the financing cost of the capital, commonly planned at 20% to 30% of inventory value a year — and the improvement shows up twice.

COGS (annual)                          = $2,400,000
Average inventory now                  = $600,000
Turnover = $2,400,000 / $600,000       = 4.0x
Days in inventory = 365 / 4.0          = 91 days

Target 6.0x turns on the same COGS:
Required inventory = $2,400,000 / 6.0  = $400,000
Cash released                          = $200,000
Days in inventory = 365 / 6.0          = 61 days
Holding cost saved at 25%              = $50,000 / yr

Reading the Trend Rather Than the Level

Because sector ranges are so wide, the level tells you less than the direction. Compute the ratio quarterly on trailing twelve-month COGS so seasonality cancels, and plot it against days on hand and fill rate on the same chart. Turnover rising with fill rate holding is genuine improvement. Turnover rising while fill rate falls is a service problem dressed up as an efficiency gain, and it will appear next quarter as lost revenue.

Quick Answer

Inventory turnover measures how many times stock sells through in a year. The formula, which inventory figure to use, sector ranges, and the cash each turn releases. This guide explains the formula in plain English, walks a worked example with real numbers, shows the mistakes to avoid, and links the free calculator so you can run your own scenario in under a minute.