Inventory Turnover Ratio in 3 Steps, From Cost to Days

The inventory turnover ratio equals cost of goods sold (COGS) divided by average inventory for the same period. It shows how many times a business sold and replaced its average stock. For annual turnover, divide 365 by the ratio to estimate days in inventory, also called days inventory outstanding (DIO). At five turns a year, inventory sells in about 73 days.

These measures help a manager decide what to order. A warehouse can turn stock quickly because customers love its products or because shelves are nearly empty. A sound interpretation connects the calculation to the goods on hand and the orders the business can actually fill.

Watch the lesson segment

The video starts at the inventory turnover segment (7:15) of a longer lesson on asset utilization ratios. Professor Farhat works from cost of goods sold and average inventory to turnover, then converts turnover to days. Watch the segment on YouTube.

How Do You Calculate The Inventory Turnover Ratio In 3 Steps?

Consider Larkspur Lighting, a hypothetical lamp maker. Its comparative balance sheet shows inventory of $70,000 at the beginning of the year and $90,000 at the end. The income statement reports $584,000 of cost of goods sold (COGS). Assume both balance-sheet dates reasonably represent normal stock levels.

Check your result another way. Larkspur sold goods costing an average of $1,600 per day ($584,000 ÷ 365). At that rate, its $80,000 average balance covers 50 days. That’s why the days formula divides by turnover. The more times inventory turns over in a year, the shorter the estimated average holding period for inventory as a whole.

You can find the inputs in two places. Cost of sales covers activity throughout the year. Each balance sheet gives a snapshot at one date. Read the inventory disclosures and the breakdown by inventory class (raw materials, work in process, and finished goods) to see which goods the balances include. The U.S. Securities and Exchange Commission (SEC) uses the same formula, cost of sales divided by average inventory, in its beginners’ guide to financial statements.

What does a faster turnover rate tell you?

Assume annual COGS stays at $584,000 and Larkspur reduces average inventory to $64,000. Turnover rises to 9.125 times, and average days fall to 40. The business now supports the same annual cost of sales with $16,000 less tied up in stock. Whether that is a good decision depends on how the reduction happened.

If Larkspur negotiated smaller, more frequent deliveries and still ships on time, it may save space, insurance, and handling costs. Fewer unsold lamps can also mean less damage, less obsolete stock to discard, and less warehouse space to light or heat.

Now suppose the reduction came from running out of the best-selling desk lamp. The ratio still rises, but customers may wait, cancel, or buy elsewhere. Ask for the number of orders filled on time and the number lost to stockouts. Those records help distinguish an improvement in stocking from sales the company never got to make.

What Is A Good Inventory Turnover Ratio?

There’s no single good number. A grocery store selling milk and bread should turn its stock far more often than a furniture maker or a jeweler. Larkspur’s 7.3 turns only mean something once you compare them with:

• Larkspur's own turnover in prior years
• Other lighting manufacturers of a similar size
• Its order fill rate, so you know a higher ratio isn't coming from empty shelves

What Does A Low Inventory Turnover Ratio Mean?

A low ratio means inventory is sitting longer. That can point to overstocking, slow-selling products, or goods going out of date. It also ties up cash and adds storage and insurance costs.

Slow-moving stock can lose value, too. Under U.S. GAAP (FASB ASC 330, Inventory), companies using FIFO or average cost write inventory down to the lower of cost and net realizable value. Net realizable value is the expected selling price minus the costs to complete and sell the goods. Companies using LIFO or the retail inventory method apply the lower of cost or market. A write-down shrinks the inventory balance, which can raise turnover in later periods even though nothing actually sold faster.

Which inputs can give a misleading answer?

Sales revenue includes the selling margin

Suppose Larkspur’s net sales were $876,000. Dividing sales by $80,000 gives 10.95. That calculation compares selling prices with the cost-based inventory balance. Raising prices could increase the result even if the same lamps moved at the same pace. Use COGS to put both figures on a cost basis.

A year-end balance can miss the busy season

If a holiday seller carries its largest stock in October and empties its shelves in December, two December balances can understate its typical investment. When available, average regularly spaced balances across the year. A more representative average can reduce the apparent turnover and lengthen the estimated days to sell.

Industry and product mix affect the comparison

Fresh bread and custom lighting have different shelf lives and production schedules. Compare a business with its own prior periods and with peers selling similar goods. Before drawing a conclusion, check period length, costing methods, seasonal buying, and whether the business consistently had the items customers wanted.

LIFO And FIFO Produce Different Ratios

The cost flow method changes both inputs. When prices are rising, LIFO (last-in, first-out) sends the newest, higher costs to COGS and leaves older, lower costs in ending inventory. FIFO (first-in, first-out) does the opposite. So a LIFO company usually reports higher turnover than an otherwise identical FIFO company.

For a FIFO-basis comparison, add each date’s LIFO reserve to that date’s reported LIFO inventory balance. Calculate average inventory using the adjusted beginning and ending balances. Adjust cost of goods sold for the change in the LIFO reserve during the same period.

FIFO COGS = LIFO COGS − (Ending LIFO reserve − Beginning LIFO reserve)

Use FIFO COGS and the adjusted average inventory together to calculate turnover on a consistent basis. IFRS (IAS 2) doesn’t allow LIFO, so this adjustment matters most for companies reporting under U.S. GAAP.

Ready to check your understanding? Take the five-question inventory turnover quiz.

Practice questions and answers

A wholesaler begins with $36,000 of inventory, ends with $44,000, and reports annual COGS of $320,000. What are turns and days?

Average inventory is $40,000. Turnover is 8 times ($320,000 ÷ $40,000), and average days to sell are 45.6 days (365 ÷ 8, rounded). Write the units beside each answer so the two measures are easy to distinguish.

A 90-day quarter has turnover of 2.25 times. How many days does that represent?

40 days. Divide the 90 days in the quarter by its 2.25 turns. Dividing 365 by a quarterly rate would mix two different periods.

A store’s turnover rises while unfilled orders double. What would you investigate?

Check which items went out of stock and when deliveries arrived. A small denominator can produce a higher ratio even as customers walk away. Match shortages to order records before recommending a further inventory reduction.

Inventory Turnover Quiz

Test your understanding of the inventory turnover formula, average inventory, seasonality, and industry comparisons. Score at least 4 out of 5 to reach 80%.

Exam Tips For CPA And CMA Candidates

Inventory turnover shows up in the financial statement ratio topics of the CPA Exam’s FAR and BAR sections, which the AICPA sets out in its exam blueprints. It also appears in Part 2, Financial Statement Analysis, of the CMA exam from the Institute of Management Accountants (IMA). Watch for these traps:

• Use COGS, not sales, unless the question tells you otherwise.
• Use the day count the question gives. With a 360-day year, Larkspur's days become 360 ÷ 7.30 = 49.3 days.
• Match the period. A quarterly turnover rate pairs with the days in that quarter.
• If only ending inventory is given, check whether the problem wants you to use it as a proxy, and say so in your answer.
• Write units next to each answer: times for turnover, days for days in inventory.

Frequently asked questions

Is 50 days the age of each lamp?

Fifty days describes the pace for the inventory as a whole. Some lamps may sell the day they arrive while others sit for months. Use item-level records to identify the slow-moving models.

Does selling a lamp mean the company has collected cash?

A credit sale moves the lamp out of inventory and creates a receivable. The time needed to collect from the customer is a separate part of the operating cycle.

What if only ending inventory is given?

Look for the preceding period’s closing balance. If the problem explicitly directs you to use ending inventory as a proxy, label that assumption. A result based on a single date may differ materially from one based on the period average.

How Is Inventory Turnover Different From Days Sales Outstanding?

Days sales outstanding (DSO) measures how long customers take to pay, using accounts receivable turnover. Add days in inventory and DSO to get the operating cycle. Subtract days payables outstanding (DPO), the time the company takes to pay its suppliers, and you get the cash conversion cycle.

Can Inventory Turnover Use Sales Instead Of COGS?

Some financial databases and older textbooks divide sales by inventory. Exam questions and most accounting courses use COGS. Before comparing two ratios, check that both use the same formula.

How Can A Business Improve Its Inventory Turnover?

Order smaller quantities more often, clear out slow-moving items, and forecast demand more carefully. Track fill rates at the same time, so a higher ratio doesn’t come from empty shelves.

Key Takeaways

• Inventory turnover = COGS ÷ average inventory. Keep both figures on a cost basis.
• Days in inventory = days in the period ÷ turnover.
• A higher ratio isn't automatically better. Check stockouts and lost orders first.
• Compare a business with its own history and with peers that sell similar goods.
• On exams, use the inputs, period, and day count the question gives you.

Inventory turnover is one of several activity ratios. See how it fits with the others in our guide to activity ratios, and pair it with profitability ratios for a fuller picture of performance.

Want more practice like this? Try the Farhat Lectures free sample course, or go deeper with the full Intermediate Accounting course.