What is the inventory turnover formula?

Inventory turnover equals cost of goods sold divided by average inventory. If your COGS for the year is 100,000 and average inventory is 20,000, turnover is 100000 / 20000 = 5, meaning you sold through and refilled your stock five times that year. Use COGS rather than sales revenue so the top and bottom of the ratio are both at cost and the number is not inflated by your markup.

How do I find average inventory?

If you have a single average figure, type it straight in. Otherwise take the beginning balance and the ending balance for the period and average them: average = (beginning + ending) / 2. For example a quarter that starts at 15,000 and ends at 25,000 has an average inventory of 20,000. Businesses with heavy seasonal swings sometimes average twelve month-end balances instead, but two-point averaging is the standard textbook method.

What is days sales of inventory and how is it calculated?

Days sales of inventory (DSI), also called days inventory outstanding, is the average number of days a unit sits in stock before it sells. The formula is DSI = days in period / turnover, usually 365 / turnover for a year. A turnover of 5 gives 365 / 5 = 73 days, so on average an item sits on the shelf for about 73 days. Lower DSI means stock moves faster and ties up less cash.

Is a high or low turnover ratio better?

Higher turnover usually means lean, efficient inventory and less cash locked in unsold goods, but pushed too far it causes stockouts and rushed, expensive reorders. Low turnover signals slow-moving or overstocked product that ages and ties up working capital. There is no universal good number: a grocery might turn 10 to 15 times a year while a furniture store turning 3 to 4 is perfectly normal. Compare against your own history and your industry.

Why do industries have such different turnover benchmarks?

Turnover tracks how perishable, fast-moving or capital-heavy the goods are. Fresh grocery turns very fast because food spoils, often 10 to 15 times a year. Apparel runs around 4 to 6 with seasonal collections. Auto parts, jewelry and furniture turn 2 to 4 because units are expensive and demand is occasional. Comparing a jeweler to a supermarket on raw turnover is meaningless, so always benchmark within your own category.

Should I use sales revenue or cost of goods sold in the formula?

Use cost of goods sold. Average inventory is carried at cost on the balance sheet, so dividing revenue by inventory mixes a retail-priced number with a cost-priced one and inflates the ratio by your gross margin. Some older textbooks use sales for a quick estimate, but for a turnover figure you can compare year over year or against a peer, COGS over average inventory is the consistent and correct choice.

Sanity-check inventory against the cash it ties up

You run a 1.2M COGS retail line and carry about 150k of average inventory. Turnover comes out at 8, DSI at roughly 46 days. That tells you a unit sits a month and a half before it sells, and that you have a month and a half of cost parked on the shelf. Before negotiating a bigger purchase order, you can see whether faster terms would free up cash or just pile on more slow stock.

Compare two product lines on a like-for-like basis

One line turns 10 times a year, another turns 3. Same store, same team, wildly different cash efficiency. Punch each line's COGS and average inventory in, read the two turnover ratios and DSIs, and you have an objective case for shifting open-to-buy budget toward the faster mover instead of arguing from gut feel about which line "sells better."

Spot a slow-moving SKU before it becomes dead stock

A category that used to turn 6 times now turns 3. Enter last year's and this year's numbers, see DSI jump from 60 to 120 days, and you have an early warning to mark it down or stop reordering while the goods still have resale value, rather than discovering a warehouse full of unsellable stock at year-end count.

Build the inventory line of an investor or lender update

A lender asks how efficiently you manage working capital. Turnover and DSI are the two numbers they expect. Compute them from your COGS and balance-sheet inventory, copy the one-line summary, and paste it straight into the update with the period clearly stated, so the figure is reproducible and not a hand-waved estimate.

Inventory Turnover Calculator — Ratio + Days Sales of Inventory

COGS ÷ average inventory = turnover ratio, plus days sales of inventory (DSI) — type the average directly or let beginning + ending fill it in — browser-only

Runs locally
Category Calculator
Best for Getting a realistic range before a purchase, plan, workout, or schedule decision.

Quick examples

Inputs

Cost of goods sold (COGS)

Average inventory

Days in period

Result

Inventory turnover

8×

Days sales of inventory (DSI)

45.6 days

What this meansHigh turnover — lean, efficient stock. Watch for stockouts and rushed reorders.

What this tool does

Free inventory turnover calculator for retail, wholesale and supply chain teams. Turnover ratio is cost of goods sold divided by average inventory, and it tells you how many times you sold through and replaced your stock in a period. Enter COGS and either the average inventory or your beginning and ending balances, and the tool returns the turnover ratio plus days sales of inventory (DSI = days in period ÷ turnover), so you can read both the rate and the calendar version of the same number. Switch the period length when your books run on a 360-day or quarterly cycle. A plain-English verdict flags whether the ratio looks lean, healthy or sluggish for general retail, so a number like 8× actually means something. Everything runs in your browser with one-click copy and a shareable URL that reproduces the exact scenario. 100% client-side, no upload, no sign-up.

Tool details

Input: Numbers; The page exposes text boxes, numeric controls, file pickers, or structured inputs depending on the tool.
Output: Live result + Copy; The result area focuses on usable output, with copy, download, or preview actions when supported.
Privacy: Browser-side processing; The main tool logic does not call an external API, so inputs normally stay in the current tab.
Save / share: Shareable URL state; Key settings are encoded in the URL so another person can reopen the same setup.
Performance budget: Initial JS <= 9 KB; No WASM budget is declared, keeping the tool quick to open on mobile.
Best fit: Calculator · Finance; Category and role tags drive related tools, internal links, and quick fit checks.

How to use

1. Input

Paste or drop your content into the tool panel.
2. Process

Click the button. All processing is local in your browser.
3. Copy / Download

Copy the result or download to disk in one click.

How Inventory Turnover Calculator fits into your work

Use it for fast estimates, comparisons, and planning numbers before you make the final call.

Calculation jobs

Getting a realistic range before a purchase, plan, workout, or schedule decision.
Comparing scenarios by changing one input at a time.
Turning rough assumptions into a number you can discuss.

Calculation checks

Double-check units, dates, rates, and rounding assumptions.
Treat health, finance, tax, and legal outputs as planning aids, not professional advice.
Save the inputs that produced an important result so you can reproduce it later.

Good next steps

These links move the current task into a more complete workflow.

Real-world use cases

Sanity-check inventory against the cash it ties up
You run a 1.2M COGS retail line and carry about 150k of average inventory. Turnover comes out at 8, DSI at roughly 46 days. That tells you a unit sits a month and a half before it sells, and that you have a month and a half of cost parked on the shelf. Before negotiating a bigger purchase order, you can see whether faster terms would free up cash or just pile on more slow stock.
Compare two product lines on a like-for-like basis
One line turns 10 times a year, another turns 3. Same store, same team, wildly different cash efficiency. Punch each line's COGS and average inventory in, read the two turnover ratios and DSIs, and you have an objective case for shifting open-to-buy budget toward the faster mover instead of arguing from gut feel about which line "sells better."
Spot a slow-moving SKU before it becomes dead stock
A category that used to turn 6 times now turns 3. Enter last year's and this year's numbers, see DSI jump from 60 to 120 days, and you have an early warning to mark it down or stop reordering while the goods still have resale value, rather than discovering a warehouse full of unsellable stock at year-end count.
Build the inventory line of an investor or lender update
A lender asks how efficiently you manage working capital. Turnover and DSI are the two numbers they expect. Compute them from your COGS and balance-sheet inventory, copy the one-line summary, and paste it straight into the update with the period clearly stated, so the figure is reproducible and not a hand-waved estimate.

Common pitfalls

Using sales revenue instead of COGS on top. Revenue carries your markup, inventory is at cost, so dividing one by the other inflates turnover by your gross margin. A line that truly turns 5 can look like it turns 8 if you slip revenue into the numerator. Always feed cost of goods sold.
Plugging in a single point-in-time inventory instead of an average. Inventory on one random day can be a seasonal peak or trough. Turnover uses average inventory; use (beginning + ending) / 2, or month-end averaging for seasonal businesses, so a December peak does not distort the whole year.
Comparing turnover across unlike industries. An 8 is excellent for furniture and mediocre for fresh grocery. Reading the raw ratio without an industry or historical benchmark leads to the wrong call. Compare against your own past periods and peers in the same category, never against a generic target.

Privacy

Every calculation — the turnover ratio, the average inventory midpoint and the DSI — is plain JavaScript that runs inside your browser tab. No COGS, inventory balance or result ever leaves the page, and nothing about what you typed is logged. The one caveat: the shareable URL encodes your numbers in the query string, so a "share link" pasted into chat will record those figures in the recipient server's access log. For a confidential financial figure, use the copy button and paste the text instead of sharing the URL.

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Inventory Turnover Calculator — Ratio + Days Sales of Inventory

What this tool does

Tool details

How to use

1. Input

2. Process

3. Copy / Download

How Inventory Turnover Calculator fits into your work

Calculation jobs

Calculation checks

Good next steps

Real-world use cases

Sanity-check inventory against the cash it ties up

Compare two product lines on a like-for-like basis

Spot a slow-moving SKU before it becomes dead stock

Build the inventory line of an investor or lender update

Common pitfalls

Privacy

FAQ

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