Inventory Turnover Ratio Calculator
Calculate the inventory turnover ratio and days inventory outstanding (DIO) from cost of goods sold and average inventory. A higher turnover generally indicates efficient inventory management.
How to use this tool
- Enter cost of goods sold (cogs), beginning inventory and ending inventory in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your inventory turnover ratio and the full breakdown beneath it.
⚠ This tool provides general estimates for education only and is not financial, tax or legal advice. Figures may not reflect your situation — verify with a qualified professional.
Formula
Inventory Turnover = COGS / Average Inventory
Average Inventory = (Beginning Inventory + Ending Inventory) / 2
Days Inventory Outstanding (DIO) = 365 / Inventory Turnover
How it works
Inventory turnover measures how many times a company sells and replaces its inventory over a period, typically a year. Cost of Goods Sold (COGS) is used as the numerator rather than revenue because both COGS and inventory are recorded at cost, making the ratio more accurate. Days Inventory Outstanding translates the turnover ratio into the average number of days goods are held before being sold.
Worked example
Retail Company with $500K COGS
- COGS = $500,000; Beginning Inventory = $80,000; Ending Inventory = $120,000
- Average Inventory = ($80,000 + $120,000) / 2 = $100,000
- Inventory Turnover = $500,000 / $100,000 = 5.00x
- Days Inventory Outstanding = 365 / 5.00 = 73.0 days
Inventory Turnover = 5.00x. On average, inventory is held for 73 days before being sold.
Common mistakes to avoid
- Using ending inventory alone instead of average inventory distorts the ratio when stock levels changed significantly during the period.
- Substituting revenue for COGS — since inventory is recorded at cost, using revenue inflates the turnover ratio and makes it incomparable to industry benchmarks that use COGS.
- Ignoring seasonality: a single annual DIO figure can be misleading for retailers with heavy Q4 inventory builds; quarterly comparisons are more informative.
Key terms
- What is inventory turnover?
- Inventory turnover is the number of times a company sells through its average inventory during a period. A ratio of 5 means the company sold and replaced its inventory 5 times during the year.
- What is a good inventory turnover ratio?
- It depends heavily on industry. Grocery retailers may turn over inventory 20+ times per year, while jewelry stores may turn it 1–2 times. Compare within your industry.
- What is Days Inventory Outstanding (DIO)?
- DIO is 365 divided by the inventory turnover ratio. It represents the average number of days a company holds inventory before selling it. Lower DIO generally means more efficient operations.
- Why use COGS instead of revenue?
- COGS and inventory are both measured at cost, so using COGS in the numerator keeps the ratio consistent. Using revenue (which includes markup) would artificially inflate the turnover ratio.
Frequently asked questions
- What is a good inventory turnover ratio?
- It varies widely by industry. Grocery retailers may turn inventory 20+ times per year, while heavy-equipment dealers may turn it 2-4 times. Always compare against industry peers rather than a universal benchmark.
- How does a higher DIO affect cash flow?
- A higher Days Inventory Outstanding means cash is tied up in unsold goods longer, reducing operating cash flow and potentially requiring more working capital financing.
- Can inventory turnover be too high?
- Yes. An extremely high ratio may indicate insufficient safety stock, leading to stockouts and lost sales. The optimal level balances holding costs against the risk of running out of inventory.