Inventory Turnover Calculator: Days Inventory Outstanding
Inventory turnover measures how efficiently a business converts its stock into sales. This calculator takes annual cost of goods sold, beginning-of-period inventory, and end-of-period inventory. It calculates average inventory automatically, then returns the inventory turnover ratio and days inventory outstanding (DIO). A dropdown lets you select your industry to see a typical turnover range as context for interpreting your result. COGS comes from the income statement in SEC 10-K or 10-Q filings. Beginning and ending inventory appear on the balance sheet: beginning inventory is the prior year-end balance, ending inventory is the current period-end balance. The IRS also requires COGS schedules for businesses filing Schedule C (Form 1040) and corporate tax returns, so these figures are well-documented in tax and financial records alike.
Formulas
Average inventory = (Beginning inventory + Ending inventory) / 2
Inventory turnover = COGS / Average inventory
Days inventory outstanding (DIO) = 365 / Inventory turnover
How to use this calculator
- Enter annual COGS from the income statement (cost of goods sold or cost of revenue line).
- Enter beginning inventory from the balance sheet at the start of the period (prior year-end for annual calculations).
- Enter ending inventory from the balance sheet at the end of the period.
- Select your industry to see a typical turnover range for context.
- Read average inventory, turnover ratio, and DIO from the output panel.
Frequently asked questions
What does the inventory turnover ratio measure?
The inventory turnover ratio measures how many times a company sells and replaces its inventory during a year. A ratio of 8 means the company cycles through its entire inventory stock eight times annually. Higher turnover generally indicates efficient inventory management and strong sales, while lower turnover may signal overstocking or slow-moving goods.
What is a high versus low inventory turnover?
High turnover (above industry average) is usually positive: products sell quickly and less cash is tied up in stock. However, turnover that is too high may mean understocking, causing lost sales. Low turnover means goods sit unsold for longer, tying up working capital and risking obsolescence. Benchmarks vary widely: grocery stores may turn inventory 15 to 30 times per year; heavy equipment manufacturers may turn it twice.
What does days inventory outstanding (DIO) mean?
DIO is the average number of days a company holds inventory before selling it. DIO = 365 divided by the turnover ratio. A DIO of 45 days means goods sit in inventory for 45 days on average before being sold. Lower DIO means faster sales cycles. DIO is part of the cash conversion cycle alongside days sales outstanding and days payable outstanding.
Should I use COGS or revenue as the denominator?
COGS is the standard and preferred denominator for inventory turnover. Using revenue inflates the ratio because revenue includes the profit margin on top of cost. For comparison across companies, always use COGS. Some analysts use revenue when COGS is not separately disclosed, but this makes cross-company comparisons less reliable.
What are typical inventory turnover ranges by industry?
Food and perishables: 20 to 40 times per year. Retail (general merchandise): 6 to 12 times. Wholesale distributors: 8 to 15 times. Manufacturing: 4 to 10 times. Automotive: 5 to 10 times. These are illustrative ranges; actual benchmarks shift with economic conditions and company strategy. Always compare against direct competitors.
Official sources
- IRS Publication 334, Tax Guide for Small Business (COGS): www.irs.gov/publications/p334.
- SEC Beginner's Guide to Financial Statements: www.sec.gov.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.