High turnover
High turnover often means inventory is selling or being consumed efficiently, which can reduce carrying costs and obsolescence risk. It can also mean inventory is too lean, causing stockouts, rush orders, or missed sales.
Inventory Turnover Ratio Calculator
Calculate inventory turnover ratio, inventory days (DSI), and average inventory from COGS plus beginning and ending inventory. Use annual, quarterly, monthly, 360-day accounting year, or custom periods for the days calculation.
Inputs
Use COGS for the same period as the inventory balances.
Inventory value at the start of the period.
Inventory value at the end of the period.
Used only to format the displayed results.
The ratio uses the period's COGS. Days inventory uses this day count.
Enter the number of days covered by the COGS and inventory balances.
Adds broad context without assuming one universal good ratio.
Advanced options
If entered, this replaces (beginning + ending) / 2.
COGS is recommended when inventory is valued at cost. Sales basis can be useful for a revenue view.
Results
Inventory turnover ratio:—
Inventory days (DSI/DIO):—
COGS:—
Average inventory:—
Formula substitution will appear after calculation.
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Compare inventory turnover over time
Enter two to five periods to compare turnover and inventory days. This uses the same period setting selected above.
| Period | COGS | Beginning inventory | Ending inventory | Turnover | Inventory days |
|---|
Methodology and privacy
Last updated June 30, 2026
Formula reviewed Uses the standard turnover formula: COGS divided by average inventory.
Privacy note Inputs stay in your browser. The calculator does not send financial values to a server.
Methodology Average inventory is calculated as beginning inventory plus ending inventory divided by two unless you provide a known average.
How to interpret inventory turnover
Low turnover
Low turnover can indicate excess stock, weak demand, obsolete inventory, slow purchasing cycles, or too much safety stock. Review item-level movement before assuming the whole operation has a demand problem.
Inventory days, DSI, and DIO
Inventory days translates turnover into time. If turnover is 6.00x over a 365-day year, inventory days is about 60.8 days. This makes the result easier to compare with lead time, shelf life, and payment terms.
Industry context matters
There is no single good ratio. Grocery, ecommerce, manufacturing, durable goods, retail, and seasonal businesses all carry different inventory levels for valid operational reasons.
Inventory turnover formulas
Average inventory: (Beginning inventory + Ending inventory) / 2
Inventory turnover ratio: COGS / Average inventory
Inventory days, DSI, or DIO: Period days / Inventory turnover
COGS is the recommended numerator when inventory is recorded at cost. A net sales basis can be useful for a revenue view, but it can be distorted by markup, discounts, and price changes.
Worked examples
Annual example
Beginning inventory is $70,000, ending inventory is $90,000, and annual COGS is $480,000.
Average inventory is ($70,000 + $90,000) / 2 = $80,000.
Inventory turnover is $480,000 / $80,000 = 6.00x.
Inventory days is 365 / 6.00 = 60.8 days.
Quarterly retail example
A retailer has quarterly COGS of $210,000, beginning inventory of $95,000, and ending inventory of $105,000.
Average inventory is ($95,000 + $105,000) / 2 = $100,000.
Quarterly turnover is $210,000 / $100,000 = 2.10x.
Inventory days is 90 / 2.10 = 42.9 days.
Common mistakes and next steps
Where to find the numbers
COGS is usually on the income statement. Beginning and ending inventory are usually balance sheet inventory balances at the start and end of the period.
Average inventory check
The common shortcut is beginning inventory plus ending inventory divided by two. Use a known average or monthly average when balances swing sharply during the period.
After a low result
Look for slow-moving SKUs, aged inventory, obsolete stock, weak demand, over-ordering, or mismatched purchasing cycles.
After a high result
Check whether fast movement is healthy or whether service levels, supplier lead times, and safety stock are too tight.
How it works
- Find COGS for the period on the income statement.
- Enter beginning inventory from the start of the period.
- Enter ending inventory from the end of the period.
- Calculate average inventory as beginning plus ending inventory divided by two.
- Divide COGS by average inventory to get inventory turnover ratio.
- Divide period days by turnover to get inventory days, DSI, or DIO.
FAQs
What is a good inventory turnover ratio?
A good ratio depends on your industry, margins, product life, demand pattern, and operating model. Compare against similar businesses and your own prior periods.
How do I calculate average inventory?
Add beginning inventory and ending inventory, then divide by two. If inventory varies heavily, use a monthly or rolling average instead.
Should I use COGS or sales?
Use COGS for the main inventory turnover ratio because inventory is valued at cost. Sales basis is optional and can be useful for revenue comparisons, but it includes markup.
What is inventory turnover vs DSI or DIO?
Turnover is the number of inventory cycles in a period. DSI or DIO converts that result into days by dividing period days by turnover.
Is higher turnover always better?
No. Higher turnover can mean efficient sales, but very high turnover may also mean understocking, stockouts, or missed sales.
How do I calculate quarterly turnover?
Use quarterly COGS, beginning inventory, ending inventory, and the quarterly preset of 90 days. Compare quarter to quarter or against the same quarter in prior years.
What does zero or negative inventory mean?
Zero or negative average inventory makes the ratio invalid. Check for missing balances, accounting timing issues, returns, write-offs, or data entry errors.
Is this calculator private?
Yes. All calculations run locally in your browser.
Disclaimer
Inventory turnover is a directional metric. Compare results across similar periods and account for seasonality and promotions.