01
Enter your COGS
The cost of the goods you sold over the period — at cost, not retail. This is the numerator of the turnover ratio.
Inventory Turnover Calculator
Inventory turnover, DSI, and supply weeks — with a benchmark verdict.
Updated Reviewed by Sajid Hussain· Editor
How fast does your stock sell?
The inventory turnover calculator that tells you what the ratio means
Inventory turnover ratio is the number of times you sell through your average inventory in a period — cost of goods sold divided by average inventory, both at cost. A ratio of 6 means you replaced your average stock six times during the year. It measures how quickly capital moves through inventory: higher means cash recycles faster and less is frozen in unsold goods; lower signals overstocking, slow movers, or oversized purchase orders. This calculator converts the bare ratio into days sales of inventory (DSI), weeks and months of supply, and a benchmark verdict — so you know not just the number but whether it's slow, healthy, or running so lean you risk stockouts.
Inventory turnover measures how quickly stock cash recycles. Every unit on a shelf is cash you can't spend on ads or new products. A turnover of 6 means you sold through your average stock six times in the year — the higher the number, the less cash is frozen at any moment. We translate the ratio into plain "you hold about X days of stock" language right on the result card.
The formula: COGS ÷ average inventory, both at cost. COGS is what the units you sold cost you. Average inventory is the typical stock held over the period. If you don't track an average, enter beginning and ending inventory and we'll average them for you.
We go beyond the bare ratio. Days sales of inventory (DSI), weeks of supply, and months of supply — the same velocity in units you actually plan around — plus a verdict against benchmarks. DSI (= 365 ÷ turnover for a year) tells you how many days of stock you hold, making overstocking and stockout risk obvious in a way the raw ratio never does.
Turnover ignores margin, and we use the at-cost basis. For gross profit per unit of inventory value, use the GMROI calculator, which layers margin on top of turnover. We divide COGS by average inventory (both at cost), not retail sales by cost-valued stock, so the ratio is accurate. And sales tax, VAT, and GST are never part of the math — they're collected and remitted, never income or cost.
Quick facts
- Headline answer
- Turnover ratio + "≈ X days of stock"
- Days sales of inventory
- DSI / DIO = period days ÷ turnover
- Supply in plain units
- Weeks and months of cover, computed for you
- Benchmark verdict
- Slow · below average · healthy · strong · very fast
- Inventory input
- Direct average, or auto-average begin + end
- Works anywhere
- Any currency · any period · no tax distortion
How it works
From COGS and stock to your turnover ratio
Four short steps — seconds to a benchmarked turnover ratio and DSI.
02
Add your inventory
Enter your average inventory at cost, or switch to beginning + ending and we'll average them for you.
03
Set the period
How many days the figures cover — 365 for a year, 91 for a quarter. We annualize the verdict so any period is judged fairly.
04
Read turnover + DSI
Get the turnover ratio, days sales of inventory, weeks and months of supply, and a verdict against the slow / healthy / very-fast benchmarks.
Steps to use the Inventory Turnover Calculator: Enter your COGS, Add your inventory, Set the period, Read turnover + DSI.
Formula
Exactly what the calculator computes
No black boxes — the inventory turnover ratio and the durations it converts into, in plain algebra.
01
Inventory turnover ratio
Inventory Turnover = Cost of Goods Sold ÷ Average Inventory (at cost)
The standard definition. Both numbers are at COST. A result of 6 means you sold through your average inventory six times during the period. This is the convention finance and accounting use.
02
Average inventory
Average Inventory = (Beginning Inventory + Ending Inventory) ÷ 2
Used when you don't track a running average. For a more accurate figure when inventory swings seasonally, average several month-end values instead of just two.
03
Days Sales of Inventory (DSI / DIO)
DSI = Period Days ÷ Inventory Turnover
The turnover ratio expressed as a duration — the average number of days a unit sits in stock before it sells. For a 365-day year, DSI = 365 ÷ turnover. It equals (Average Inventory ÷ COGS) × Period Days.
04
Weeks & months of supply
Weeks of Supply = (Period Days ÷ 7) ÷ Turnover · Months of Supply = (Period Days ÷ 30.42) ÷ Turnover
The same velocity in friendlier planning units. 30.42 is the average calendar month (365 ÷ 12). Weeks and months of supply tell you how long your current average stock would last at the period's sell-through rate.
05
Annualized turnover (for the verdict)
Annualized Turnover = Turnover × (365 ÷ Period Days)
So a quarter of data is benchmarked on the same yearly scale as a full year. For a 365-day period this leaves turnover unchanged. The verdict bands always apply to annualized turns per year.
Worked example
1.2M COGS, 200k average inventory, one year
Watch the ratio convert into days, weeks, and months of supply.
Scenario
A store sold goods that cost $1,200,000.00 over a 365-day year and carried $200,000.00 of inventory on average (at cost). How fast is its stock turning?
1
Step 1 · Inventory turnover
COGS ÷ average inventory at cost: $1,200,000.00 ÷ $200,000.00 = 6.0. The store sold through its average inventory 6.0 times during the year.
Turnover: 6.0× per year
2
Step 2 · Days sales of inventory
Period days ÷ turnover: 365 ÷ 6.0 = 60.83 days. On average a unit sits in stock about 61 days before it sells.
DSI: 60.83 days
3
Step 3 · Weeks of supply
Weeks in the period ÷ turnover: (365 ÷ 7 = 52.14) ÷ 6.0 = 8.69 weeks of cover at this sell-through rate.
Weeks of supply: 8.69
4
Step 4 · Months of supply
Months in the period ÷ turnover: (365 ÷ 30.42 = 12) ÷ 6.0 = 2.0 months of cover. Plan your reorder cadence around this.
Months of supply: 2.0
The takeaway
At 6.0 turns a year — about 61 days of stock — this store sits in the strong band: inventory works hard and cash isn't idle. If you also wanted the gross profit earned per unit of currency tied up in that inventory, you'd layer margin on top with the GMROI calculator. Turnover alone is pure velocity.
Industry benchmarks
What inventory turnover to aim for
General turnover bands (turns per year) and the days of stock they imply. Targets vary a lot by category — grocery turns far faster than furniture or jewelry — so treat these as a starting reference, not a universal rule.
| Metric | Poor | Average | Good | Excellent |
|---|---|---|---|---|
Turnover (turns / year) CSIMarket Industry Comparison 2025 | < 2 | 2–4 | 4–6 | 6–12 |
Days sales of inventory NYU Stern Sector Financial Data 2025 | > 180 | 90–180 | 60–90 | 30–60 |
Grocery / fast-moving Food Marketing Institute Supermarket Facts 2024 | < 8 | 8–12 | 12–20 | 20+ |
Apparel / specialty NRF Retail Benchmarks 2025 | < 2 | 2–4 | 4–6 | 6+ |
Furniture / durables American Home Furnishings Alliance Data 2024 | < 1 | 1–2 | 2–4 | 4+ |
Very fast (watch stockouts) Shopify Ecommerce Benchmarks 2025 | — | — | — | > 12 |
Why this calculator
Calcrux vs other inventory turnover calculators
Most turnover tools print the bare ratio and leave you guessing what it means. We convert it into days, weeks, and months, benchmark it, and flag overstocking and stockout risk.
| Feature | Calcrux | Omni Calculator | Spreadsheet |
|---|---|---|---|
| Inventory turnover ratio | Manual | ||
| Days sales of inventory (DSI / DIO) | Rare | Manual | |
| Weeks AND months of supply | Manual | ||
| Benchmark verdict (slow → very fast) | |||
| Flags overstocking & stockout risk | |||
| Annualizes any period for the verdict | Manual | ||
| Auto-averages beginning + ending inv | Rare | Manual | |
| Uses correct at-cost basis (not sales) | Often wrong | Manual | |
| Guards divide-by-zero (no NaN) | Often breaks | Manual | |
| Works in any currency | Most US-only |
Common mistakes
Where inventory turnover goes wrong
Using sales instead of COGS in the numerator
Why it matters
Some calculators divide total sales (at retail) by average inventory (at cost). Mixing a retail numerator with a cost denominator inflates turnover — often by your full markup — and makes you look far leaner than you are.
Fix
Use cost of goods sold ÷ average inventory, both at cost. That's the accounting convention this calculator uses. Sales ÷ inventory is a different, looser metric.
Valuing inventory at retail instead of cost
Why it matters
If the denominator is at retail but COGS is at cost, the ratio is understated. The two figures must be on the same cost basis to mean anything.
Fix
Always enter average inventory AT COST — the same basis as your COGS. Every inventory field here is labeled "at cost" to keep them aligned.
Comparing turnover across very different categories
Why it matters
Grocery runs on razor-thin margins and very fast turns; furniture and jewelry turn slowly on fat margins. A "good" turnover in one category is a red flag in another, so blanket targets mislead.
Fix
Benchmark within your own category, and use the per-category rows above as a starting reference rather than one universal number.
Confusing turnover with GMROI
Why it matters
Turnover only measures velocity — how fast stock moves. It says nothing about how profitable those sales are. You can turn inventory ten times a year and still lose money on thin or negative margins.
Fix
Use turnover for velocity and GMROI when you need profit per unit of inventory value. Our GMROI calculator multiplies turnover by gross margin %; the two answer different questions.
Using a single snapshot of inventory
Why it matters
Inventory swings with seasonality and restocks. A single month-end figure can sit far above or below your true average, throwing the ratio and DSI off.
Fix
Use a genuine average, or at least average beginning and ending inventory — the calculator does this in begin/end mode. Better still, average several month-end values.
Forgetting to annualize a partial period
Why it matters
A quarter's turnover of 1.5 looks slow until you realize it annualizes to 6. Reading the raw partial-period ratio against yearly benchmarks understates your real velocity.
Fix
Tell the calculator the period length in days. We annualize the verdict for you (turnover × 365 ÷ period days) so a quarter is judged on a yearly scale.
Tips
Turn stock faster on purpose
Watch DSI, not just the ratio
Days sales of inventory is easier to act on than a bare number. "61 days of stock" tells you instantly whether you're overbuying. Track DSI trending down over time.
Order smaller, more often
Smaller, more frequent reorders lower your average inventory without losing sales — a direct turnover boost. Pair this with our EOQ calculator to find the order size that minimizes total cost.
Clear slow movers to lift turnover
Dead stock inflates average inventory and drags turnover down. Marking it down to free up cash often raises overall turnover even at a lower margin on those units.
Track turnover by SKU, not just overall
A healthy blended turnover can hide a handful of cash-trap SKUs. Run the numbers per product to find what to cut, reprice, or stop reordering.
Don't chase turnover into stockouts
Pushing turnover too high (above ~12/yr for most catalogs) starts costing you sales when items go out of stock. Balance velocity against service level and safety stock.
Pair turnover with GMROI
Turnover tells you how fast stock moves; GMROI tells you how much profit it earns per unit of inventory value. Reading both together stops you from optimizing velocity at the expense of profit.
Use cases
When sellers reach for inventory turnover
The Inventory Turnover Calculator works across every stage of the workflow.
Spotting overstocked SKUs
Rank products by turnover or DSI to find the ones tying up cash. A SKU sitting on 200+ days of stock is a markdown or stop-reorder candidate.
Setting reorder cadence
Months of supply tells you how long current stock lasts, so you can time purchase orders to land just before you run dry instead of overbuying.
Reviewing a category's health
Roll up COGS and inventory for a whole category to see whether the line as a whole moves fast enough to justify the cash it consumes.
Freeing up working capital
Show finance how much cash is frozen in slow stock. Lifting turnover from 3 to 5 can release a large chunk of working capital without cutting sales.
Comparing suppliers or lead times
A faster-shipping supplier lets you hold less safety stock and lift turnover. DSI quantifies how many days of inventory each option requires.
Reporting to investors or a lender
Inventory turnover and days inventory outstanding are recognized efficiency metrics — a clean way to show that inventory, often the biggest asset, isn't sitting idle.
Glossary
Inventory velocity vocabulary
Every important term you'll encounter in this calculator and the broader topic.
- Inventory turnover
- How many times you sold through your average inventory in a period. The ratio is COGS ÷ average inventory, both valued at cost. Higher means faster-moving stock.
- Inventory turnover ratio
- Another name for inventory turnover — the single number (e.g. 6.0) that the formula produces.
- Days Sales of Inventory (DSI)
- The turnover ratio expressed as a duration: the average number of days a unit sits in stock before selling. DSI = period days ÷ turnover.
- Days Inventory Outstanding (DIO)
- A synonym for DSI, common in finance. Part of the cash conversion cycle alongside days sales outstanding and days payable outstanding.
- COGS
- Cost of Goods Sold — the landed cost (goods + inbound freight) of the items you actually sold in the period. The numerator of turnover.
- Average inventory (at cost)
- The typical value of stock you hold over the period, valued at what it cost you, not its retail price. The denominator of turnover.
- Weeks / months of supply
- Your average inventory expressed as the number of weeks or months it would last at the period's sell-through rate — handy for planning reorders.
- Stock turn
- A retailer's shorthand for inventory turnover — one full cycle of selling through and replacing the average stock.
- GMROI
- Gross Margin Return On Investment — gross profit per unit of inventory value. Turnover times gross margin %. Use the GMROI calculator when you need profit, not just velocity.
Help & answers
Frequently asked questions
Everything you need to know about how the Inventory Turnover Calculator works.
01What is inventory turnover and what does it tell you?
Inventory turnover is how many times you sold through your average inventory. A turnover of 6 means you sold and replaced stock six times. It measures velocity — how quickly cash tied up in inventory recycles. High = less cash frozen in stock; low = overstocking or slow movers.
02How do you calculate inventory turnover?
Inventory turnover = COGS ÷ average inventory, both at cost. Average inventory = (beginning + ending) ÷ 2. Example: 1,200,000 in COGS on 200,000 average inventory = 6.0 turns. This calculator does the math and benchmarks the result.
03What is days sales of inventory (DSI)?
DSI (also called DIO) = period days ÷ inventory turnover. For a 365-day year, a turnover of 6 gives about 61 days of stock. It tells you directly how many days of inventory you're holding, making overstocking and stockout risk more concrete than the bare ratio.
04What is a good inventory turnover ratio?
Below 2 turns a year usually signals overstocking; 2–4 is workable; 4–6 is healthy for many catalogs; 6–12 is strong; above 12 is very fast (watch for stockouts). Targets vary by industry: grocery turns 10–20+; furniture turns 1–4. Compare within your own category.
05What is the difference between inventory turnover and GMROI?
Turnover measures velocity only and ignores profit. GMROI multiplies turnover by gross margin %, so it shows how much gross profit each unit of inventory value earns. Turnover answers "how fast?"; GMROI answers "how profitable per unit invested?".
06Should I use COGS or sales to calculate inventory turnover?
Use COGS, not sales. The convention is COGS ÷ average inventory, both at cost. Using retail sales as the numerator inflates turnover by roughly your markup, making stock look leaner than it is. Sales ÷ inventory is a different, looser metric.
07How do I average my inventory if I don't track an average?
Average beginning and ending inventory: (beginning + ending) ÷ 2. Switch to "Average from beginning + ending" mode and enter both at cost. For seasonal businesses, averaging several month-end values is more accurate than just two.
08Can I calculate turnover for a quarter or a month instead of a year?
Yes. Enter the period length in days (91 for a quarter, 30 for a month) and the calculator computes turnover and DSI for that window. The verdict is annualized (turnover × 365 ÷ period days), so a quarterly 1.5 is benchmarked as the 6 turns a year it represents.
09What does a very low inventory turnover mean?
Under ~2 turns a year usually means overstocking, slow movers, or oversized purchase orders. It ties up cash and raises obsolescence risk. The fix: order smaller and more often, clear slow movers with markdowns, or stop reordering the worst performers.
10What does a very high inventory turnover mean?
Very high turnover (above ~12/yr for most catalogs) means stock sells fast and little cash is tied up. But if it's too high you may be losing sales to stockouts. The goal isn't the highest number — it's the highest you can sustain. Check reorder points and safety stock.
11Does the inventory turnover calculator work in any currency?
Yes. Turnover, DSI, and supply weeks/months are pure ratios and durations with no currency. Enter COGS and inventory in your local currency and the ratio is the same. We keep sales tax, VAT, and GST out of the math entirely.
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Category
Ecommerce Seller Operations
Subcategory
inventory operations
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Global · 9 markets
Price
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Topics
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