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Inventory Turnover Calculator

Calculate inventory turnover from COGS and average inventory, plus days inventory outstanding, sell-through rate and GMROI, annualised from any period.

$125,000.00
Average inventory
3.20×
Turnover for the period
3.20×
Annualised turnover
114.1 d
Days inventory outstanding
30.0%
Sell-through rate
$160,000.00
Gross margin
28.6%
Gross margin %
1.28
GMROI
16.3 wk
Weeks of supply on hand
22.3%
Inventory as % of revenue

Two to six turns a year is normal for general merchandise, apparel and B2B distribution.

Every $1 tied up in inventory at cost returns $1.28 in gross margin — above the break-even 1.00 that retail buyers use as a floor.

Inventory turnover is cost of goods sold ÷ average inventory, where average inventory is (beginning + ending) ÷ 2. Days inventory outstanding is the period length ÷ turnover, so a quarterly turnover of 0.8 over 91 days is about 114 days of stock. Annualised turnover scales the period figure by 365 ÷ period days so a monthly and an annual reading can be compared. Sell-through is units sold ÷ units received, and GMROI is gross margin currency ÷ average inventory at cost. Some analysts substitute sales for COGS in the turnover ratio, which inflates it by the gross margin — this tool uses COGS, the convention on which the healthy-range guidance above is based. All maths runs locally in your browser.

What is the Inventory Turnover Calculator?

Inventory turnover tells you how many times you sell and replace your stock in a period. This calculator divides cost of goods sold by average inventory — the average of your beginning and ending balances — and converts the result into days inventory outstanding, so you can see in plain days how long stock sits before it moves.

  • Turnover ratio for the period and annualised for comparison
  • Days inventory outstanding and weeks of supply on hand
  • Sell-through rate from units sold versus units received
  • GMROI and gross margin percentage from revenue and COGS
  • Interpretation bands for fast, normal and slow-moving stock
  • 100% local — inventory and cost data never leaves your device

How to use the Inventory Turnover Calculator

  1. 1

    Choose the period your figures cover — year, quarter, month or week.

  2. 2

    Enter cost of goods sold and sales revenue for that period.

  3. 3

    Enter beginning and ending inventory at cost so the tool can average them.

  4. 4

    Add units sold and units received to get the sell-through rate.

  5. 5

    Read turnover, days inventory outstanding, GMROI and weeks of supply below.

About the Inventory Turnover Calculator

Inventory turnover tells you how many times you sell and replace your stock in a period. This calculator divides cost of goods sold by average inventory — the average of your beginning and ending balances — and converts the result into days inventory outstanding, so you can see in plain days how long stock sits before it moves.

It also covers the retail measures that sit alongside turnover: sell-through rate from units sold against units received, gross margin return on inventory investment (GMROI), gross margin percentage and weeks of supply on hand. A period selector annualises correctly, so a monthly reading can be compared with an annual one.

Interpretation bands under the results say whether your annualised turnover reads as fast, normal or slow, without pretending there is a single right answer — twelve turns is routine in fresh food and unheard of in jewellery. All the maths happens in your browser and nothing you type is uploaded or stored. Figures are estimates for planning and buying decisions, not financial advice.

Frequently asked questions

What is a good inventory turnover ratio?

It depends entirely on the category. Grocery and fresh food often turn twelve or more times a year, general retail and distribution two to six, and jewellery or heavy machinery less than two. Compare yourself with your own history and your category, not a universal target.

How do you calculate days inventory outstanding?

Divide the period length by the turnover ratio for that period. With an annual turnover of 3.2, days inventory outstanding is 365 ÷ 3.2, or about 114 days — the average time a unit sits in stock before it sells.

Should inventory turnover use sales or COGS?

Use cost of goods sold. Both figures are inventory measured at cost, so using sales inflates the ratio by your gross margin and makes performance look better than it is. This tool uses COGS, which is the standard definition.

What is GMROI and what is a good number?

GMROI is gross margin currency divided by average inventory at cost, so it shows how much margin each unit of inventory investment returns. Anything above 1.00 means the stock earns more than it costs to hold; many retailers target 2.00 or better.

What is the difference between turnover and sell-through rate?

Turnover compares cost of goods sold against average inventory value across a period. Sell-through compares units sold against units received, usually for one season or delivery. Sell-through answers 'did this buy work', turnover answers 'is the whole stockholding efficient'.

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