“What is a good inventory turnover ratio?” is one of the most common questions in inventory management, and the honest answer is: it depends. A ratio that is excellent for one business can be a warning sign for another. This article explains how to calculate turnover, why a single benchmark can mislead you and how to use the ratio to make better decisions.
The formula
Inventory turnover measures how many times you use or sell your average inventory in a period, usually a year.
- Inventory turnover = cost of goods sold ÷ average inventory value
Average inventory is usually the beginning value plus the ending value, divided by two. Monthly averages give a more accurate result if your inventory changes a lot during the year.
A related measure converts turnover into days:
- Days of inventory on hand = 365 ÷ inventory turnover
For example, a turnover of 5 means you hold roughly 73 days of inventory. You can run your own numbers with our free inventory turnover calculator.
Why there is no single good number
Turnover depends heavily on the type of business. A few factors that change what “good” looks like:
- Industry: a food producer with perishable ingredients turns inventory much faster than a maker of heavy equipment with long build cycles.
- Business model: make-to-order shops may hold little finished goods, while make-to-stock businesses carry more.
- Lead times: long supplier lead times, especially for imported parts, require more inventory in the pipeline.
- Service promise: if customers expect same-day shipment, you need more stock on hand.
- Product mix: a business with many slow-moving spare parts will show lower turnover than one with a few fast movers.
Published industry averages can be useful for broad context, but check how they were calculated before comparing. Different sources use different definitions, for example sales instead of cost of goods sold. If you use a benchmark, cite where it came from and make sure the formula matches yours.
Better comparisons
Compare against yourself
The most useful comparison is your own trend over time. If turnover is falling while sales are steady, inventory is growing faster than the business needs. If it is rising while service holds steady, your planning is improving.
Compare by category
A single company-wide number hides a lot. Calculate turnover for raw materials, work-in-progress and finished goods separately, and by product family. ABC/XYZ classification helps you see which groups of items drag the average down.
Compare with service
Turnover alone does not tell you whether customers are happy. High turnover with frequent stockouts is not a success. Track turnover alongside a service measure, such as on-time shipments or fill rate.
What low turnover often means
Low turnover is often a sign of one or more of these issues:
- Slow-moving or dead stock that nobody has reviewed. See how to find and clear dead stock.
- Safety stock set too high or based on old lead times. See the safety stock formula guide.
- Order quantities driven by supplier minimums. See EOQ vs MOQ.
- Purchasing for a forecast that did not happen.
What very high turnover can mean
High turnover is usually good, but it can also mean stock is too thin. Watch for frequent expediting, rush freight and production waiting on parts. These costs do not show up in the turnover ratio but affect your margin.
Using turnover well
- Calculate it the same way every time.
- Review it monthly or quarterly, by category.
- Pair it with a service measure.
- Investigate changes rather than chasing a target number.
For all of our free calculators and formula guides, visit the free supply chain tools page. If you would like help finding what is behind your turnover numbers, see inventory optimization consulting.
Frequently asked questions
Should we use cost of goods sold or sales?
Cost of goods sold is generally preferred, because inventory is valued at cost. Using sales inflates the ratio. Whichever you choose, use it consistently.
How often should we calculate turnover?
Monthly or quarterly is common. Use the same method each time so the trend is meaningful.
Can turnover be too high?
Yes, if it comes with frequent stockouts, rush freight or production delays. Always look at turnover alongside a service measure.
What is the quickest way to improve turnover?
Usually, stop buying items you already have too much of, and review slow-moving stock. Updating reorder points and safety stock with current data often helps too.