What Is Inventory Turnover? (And What's a Healthy Ratio)

The formula and why COGS, not sales

Inventory turnover = cost of goods sold ÷ average inventory. COGS is what the sold goods cost you to buy or make; average inventory is the typical value of stock on your shelves, calculated as (opening + closing inventory) ÷ 2 to smooth out seasonal swings. The result is a count of how many times you cycled through your stock.

Turnover uses COGS, not sales revenue, because inventory is recorded at cost. Using revenue would mix your markup into the ratio and inflate it, making stock look like it moves faster than it does. To keep the comparison honest — cost against cost — always divide the cost of goods sold by inventory valued at cost.

What a healthy ratio looks like

There is no universal good number — it depends entirely on the industry. Grocery and fresh food turn over dozens of times a year because stock spoils. Fashion retail often lands between 4 and 6. Furniture, jewelry and specialty goods may sit at 1 to 2, since each item is expensive and sells slowly. Judge your ratio against competitors in your own sector, not a headline figure.

A companion metric makes turnover tangible: days inventory outstanding = 365 ÷ turnover. A turnover of 6 means 365 ÷ 6 ≈ 61 days — stock sits on the shelf about two months on average. Falling turnover (rising days) warns of overstocking or slowing demand; a sudden jump can signal you are running too lean and risking stockouts.

Why turnover ties up your cash

Every unit on the shelf is cash you have already spent and cannot use. Slow turnover means money is frozen in inventory instead of paying wages, buying faster-selling stock, or earning elsewhere. Speeding turnover from 4 to 6 on the same $100,000 average inventory frees the same sales to run on less capital — a direct boost to cash flow.

But faster is not always better. Push turnover too high by carrying too little stock and you risk empty shelves, lost sales and disappointed customers. The goal is not the maximum ratio but the right balance — enough stock to meet demand reliably, without so much that cash and shelf space go to waste.

Frequently asked questions

How do I calculate average inventory?

Add the inventory value at the start of the period to the value at the end, then divide by 2. This smooths out seasonal peaks so the turnover ratio reflects a typical stock level.

Is a high inventory turnover always good?

Usually it signals efficient selling and low tied-up capital, but very high turnover can mean you hold too little stock and lose sales to stockouts. Aim for a balance suited to your demand.

What are days inventory outstanding?

Days inventory outstanding = 365 ÷ turnover. It converts the ratio into the average number of days stock sits before it sells — a turnover of 5 means about 73 days on the shelf.

Should I use COGS or sales in the formula?

Use cost of goods sold. Inventory is carried at cost, so dividing COGS by inventory keeps both sides on a cost basis. Using sales revenue would build your markup into the ratio and overstate turnover.