How is the inventory turnover ratio calculated?

The inventory turnover ratio is calculated by dividing the cost of goods sold (COGS) by the average inventory. Average inventory is the sum of opening and closing inventory divided by two. For example, if COGS is $100,000 and average inventory is $25,000, the turnover ratio is 4.

What does days inventory mean?

Days inventory (or days sales of inventory) indicates how many days on average it takes to sell the entire inventory. It is calculated by dividing the number of days in the period by the inventory turnover ratio. For instance, if the period is 365 days and turnover is 5, days inventory is 73 days.

Why is the period length optional?

The period length is optional because the inventory turnover ratio itself does not require it. However, if you want to calculate days inventory, you need to specify the number of days in the reporting period (e.g., 365 for a year, 90 for a quarter). Without it, only the turnover ratio is provided.

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Inventory Turnover Calculator.

Aug 5, 2026

Measure how often inventory is sold during a consistent reporting period.

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02 / ANSWER

Cost of goods sold

Opening inventory

Closing inventory

Period length

Average inventory

$25,000.00

Inventory turnover

Days inventory

91.3days

Turnover uses COGS ÷ ((opening inventory + closing inventory) ÷ 2). Keep all values in the same currency and period.

FAQs

How is inventory turnover calculated?

Inventory turnover is COGS divided by average inventory, where average inventory is the opening and closing balance average.

What period should I use?

Use COGS and inventory balances from the same reporting period and label the period length consistently.

How to Use the Inventory Turnover Calculator

Enter COGS, opening inventory, closing inventory, and the reporting period.

Use COGS and inventory balances from the same reporting period.
Enter opening and closing inventory values.
Review turnover and days of inventory on hand.

Inventory Turnover Formula

Turnover

Turnover = COGS ÷ ((Opening inventory + Closing inventory) ÷ 2)

The simple average inventory method is used; period consistency matters.

Real-World Use Cases

Stock Planning

Compare how quickly inventory moves between periods.

Working Capital

Identify slow-moving inventory for further review.

Tips

Use a consistent accounting period and valuation basis.
A high turnover rate is not automatically better; compare it with stockouts and margins.

Common Mistakes to Avoid

Using revenue instead of COGS.
Using only one ending inventory balance without the opening balance.

Related Calculators

Days Inventory Outstanding CalculatorCalculate inventory days from average inventory, COGS, and reporting-period days.COGS CalculatorCalculate cost of goods sold from beginning inventory, purchases, and ending inventory.Ending Inventory CalculatorCalculate ending inventory from explicit user inputs with transparent assumptions and instant, debounced results.Accounts Payable Turnover CalculatorCalculates how many times a company pays off its accounts payable during a period, indicating payment efficiency.Days Payable Outstanding CalculatorCalculate payable days using average payables and an explicitly labeled COGS proxy.Fixed Asset Turnover CalculatorCalculate fixed asset turnover from explicit user inputs with transparent assumptions and instant, debounced results.

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Canonical URL: https://mathify.one/en/business/inventory-turnover

Updated Aug 5, 2026

Cite as: Mathify. (2026). Inventory Turnover Calculator. https://mathify.one/en/business/inventory-turnover

Use Cases

Assess inventory efficiency

Business owners and managers use the turnover ratio to evaluate how efficiently inventory is managed. A higher ratio indicates faster selling and less money tied up in stock.

Example: A retailer with COGS of $500,000 and average inventory of $100,000 has a turnover of 5, meaning inventory sells five times a year.

Plan purchasing and cash flow

Knowing days inventory helps in planning reorder schedules and managing cash flow. It shows how long current stock will last, aiding in budget and procurement decisions.

Example: If days inventory is 60, you know you have about two months of stock on hand, so you can time your next purchase accordingly.

Frequently Asked Questions

How is the inventory turnover ratio calculated?: The inventory turnover ratio is calculated by dividing the cost of goods sold (COGS) by the average inventory. Average inventory is the sum of opening and closing inventory divided by two. For example, if COGS is $100,000 and average inventory is $25,000, the turnover ratio is 4.
What does days inventory mean?: Days inventory (or days sales of inventory) indicates how many days on average it takes to sell the entire inventory. It is calculated by dividing the number of days in the period by the inventory turnover ratio. For instance, if the period is 365 days and turnover is 5, days inventory is 73 days.
Why is the period length optional?: The period length is optional because the inventory turnover ratio itself does not require it. However, if you want to calculate days inventory, you need to specify the number of days in the reporting period (e.g., 365 for a year, 90 for a quarter). Without it, only the turnover ratio is provided.

Tips & Common Mistakes

Tips

Use accurate COGS and inventory values from your financial statements for the most reliable results.
Ensure opening and closing inventory are for the same period to get a correct average.
Compare your turnover ratio with industry benchmarks to gauge performance.
If you calculate days inventory, use the actual number of days in your reporting period (e.g., 365 for a year, 90 for a quarter).

Common Mistakes to Avoid

Using sales revenue instead of cost of goods sold (COGS) – this inflates the turnover ratio.
Forgetting to average the inventory – using only closing inventory can skew the result.
Mixing different period lengths when comparing turnover ratios – always use the same period for consistency.

Last updated: August 13, 2026