Stock Turn Calculator with Weeks of Cover
This stock turn calculator shows how many times the average inventory was sold in a period (cost of goods sold ÷ average inventory at cost), how many days of stock that means, and how many weeks the current stock will last at the current rate of sale. Stock turn is also called inventory turnover.
Stock turn = COGS ÷ average inventory. Days of stock = days in period ÷ stock turn. Weeks of cover = current stock ÷ average weekly sales.
The numbers stay in your browser and are not sent anywhere.
How to Use the Stock Turn Calculator
- Enter the cost of goods sold for the period, for example the last 12 months.
- Enter the average inventory at cost for the same period: the average of the month-end stock values works well.
- Enter the number of days in the period (365 for a year, 91 for a quarter).
- For weeks of cover, enter the current stock in units and the average weekly units sold over the last four to six weeks.
Stock Turn Formula and Weeks of Cover Formula
Stock turn and days of stock describe the past period and suit season or year reviews. Weeks of cover looks forward and suits weekly decisions: reorders, transfers and the timing of markdowns. Keep cost and inventory on the same basis; mixing sales at retail price with stock at cost overstates the turn. My article on retail KPIs for fashion brands shows how stock turn fits with sell-through, GMROI and margin.
Stock Turn and Weeks of Cover Worked Example
An illustrative accessories category sold goods costing 600,000 over a year, with an average inventory of 150,000 at cost. The stock turn is 600,000 ÷ 150,000 = 4, so the stock was sold four times, and 365 ÷ 4 gives about 91 days of stock. Today the category holds 1,200 units and sells about 150 units a week, so it has 1,200 ÷ 150 = 8 weeks of cover. If the season ends in five weeks, three weeks of stock are at risk of markdown.
Common Mistakes in Stock Turn Calculations
- Dividing sales at retail price by inventory at cost.
- Using closing stock instead of an average, which distorts the turn in seasonal businesses.
- Comparing a quarterly stock turn with an annual one without converting the period.
- Calculating weeks of cover from one unusual week, such as a promotion week.
- Reading one high total turn while slow categories hide behind fast basics.
Stock Turn Calculator FAQ
Stock turn equals cost of goods sold divided by average inventory at cost, for the same period. Goods costing 600,000 sold against an average stock of 150,000 give a stock turn of 4. Some retailers use sales and inventory at retail price instead; the key is to use the same basis for both.
Yes. Stock turn is the usual UK retail term and inventory turnover the usual accounting term for the same ratio. Both show how many times the average stock was sold in a period.
Divide the current stock in units by the average weekly units sold. 1,200 units selling 150 a week gives 8 weeks of cover. Use an average of several recent weeks so one promotion does not distort it.
It varies with the business model and category: basics and continuous lines turn faster than seasonal collections with deep size runs. Compare each category with its own history and plan rather than with a general benchmark. A falling turn is an early sign that the buy is ahead of demand.
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