Inventory Turnover Calculator

Inventory turnover is how many times you sold through your average inventory during a period — usually a year. A turnover of 6 means you sold and replaced your average stock six times. It measures velocity: how quickly the cash you have tied up in inventory recycles back into sales. A higher ratio means less cash frozen in stock at any moment, while a low ratio signals overstocking or slow-moving products.

The formula is inventory turnover = cost of goods sold (COGS) ÷ average inventory, with both values at cost. COGS is what the units you actually sold cost you over the period. Average inventory is the typical value of stock you held — often calculated as (beginning inventory + ending inventory) ÷ 2. For example, $1,200,000 of COGS against $200,000 of average inventory is a turnover of 6.0. This calculator does the math and benchmarks the result for you.

Days sales of inventory (DSI), also called days inventory outstanding (DIO), is the inventory turnover ratio expressed as a duration: the average number of days a unit sits in stock before it sells. The formula is period days ÷ turnover, so for a 365-day year a turnover of 6 is about 61 days of stock. DSI is often easier to act on than the bare ratio because it tells you directly how much stock you're holding in days.

As a rough guide, below 2 turns a year usually signals overstocking, 2–4 is workable but below average, 4–6 is healthy for many catalogs, 6–12 is strong, and above 12 is very fast (watch for stockouts). But targets vary enormously by industry: grocery and other fast-moving goods often turn 10–20+ times a year on thin margins, while furniture, jewelry, and other durables turn 1–4 times on fatter margins. Always compare within your own category rather than to a single universal number.

Inventory turnover only measures velocity — how fast stock moves — and ignores profit entirely. You could turn inventory ten times a year and still lose money if your margins are negative. GMROI (gross margin return on investment) multiplies turnover by your gross margin %, so it tells you how much gross profit each dollar of inventory earns. Turnover answers "how fast?"; GMROI answers "how profitable per dollar invested?". Use our GMROI calculator when you need the profit side too.

Use COGS, not sales. The accounting convention is COGS ÷ average inventory, with both figures valued at cost so they're on the same basis. Some calculators divide retail sales by cost-valued inventory, which mixes bases and inflates turnover by roughly your markup — making your stock look far leaner than it is. This calculator uses the correct at-cost basis. Sales ÷ inventory (the sales-to-stock ratio) is a different, looser metric.

The simplest approach is to average your beginning-of-period and end-of-period inventory: (beginning + ending) ÷ 2. This calculator does that for you — switch the inventory mode to "Average it from beginning + ending inventory" and enter both at cost. For a more accurate figure when inventory swings seasonally, average several month-end values instead of just two, then enter that as your average inventory at cost.

Yes. Enter the period length in days — 91 for a quarter, 30 or 31 for a month — and the calculator computes turnover and DSI for that exact window. Because raw partial-period turnover (say 1.5 for a quarter) is hard to compare against yearly benchmarks, the verdict is annualized for you (turnover × 365 ÷ period days), so a 1.5 quarterly turnover is judged as the 6 turns a year it really represents.

A low turnover — under about 2 turns a year for most catalogs — means stock is sitting a long time before it sells, which usually points to overstocking, slow-moving or dead products, or overly large purchase orders. It ties up cash you could use elsewhere and raises the risk of obsolescence and storage cost. The fix is usually to order smaller and more often, clear slow movers with markdowns, or stop reordering the worst performers.

A very high turnover — above roughly 12 turns a year for most catalogs — means stock sells through extremely fast and very little cash is tied up. That's efficient, but if it's too high it can mean you're running on thin buffers and losing sales to stockouts. The goal isn't the highest possible number; it's the highest turnover you can sustain without running out of stock. Check that your reorder points and lead times leave enough safety stock.

Yes. Inventory turnover, DSI, and weeks/months of supply are pure ratios and durations — they have no currency at all. Enter your COGS and inventory in whatever currency you trade in (USD, INR, GBP, EUR, and more) and the turnover ratio comes out identical. The only money shown is your average inventory figure, which we display back in your own currency. We also keep sales tax, VAT, and GST out of the math entirely, since those are collected and remitted, never income or cost.