Stock Cover Calculator (Days and Weeks of Supply)

Find out how long your current stock will last at your current sales rate. Enter your own numbers, no account needed.

By Tibeau De Grauwe, FounderUpdated September 2026

  • 25 products free
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  • 10-min setup

Stock cover (also called days of supply or days on hand) measures how many days your current stock will last at the current rate of demand. It is one of the quickest ways to spot both stockout risk and overstock.

Enter your current stock on hand and your average daily demand for the item. Use a recent average, for example the last 30 to 90 days, and remove one-off spikes such as a single bulk order.

For an item with a 14-day supplier lead time, a stock cover of 10 days means you will run out before a new order arrives. A cover far above your reorder cycle points to excess stock tying up cash.

Stock Cover Calculator

units
units/day

Stock cover

30 days

≈ 4.29 [object Object]

How the calculation works

Stock cover (days) = stock on hand ÷ average daily demand. Stock cover (weeks) = days ÷ 7.

Example: 1,200 units on hand and 40 units sold per day gives 1,200 ÷ 40 = 30 days, or about 4.3 weeks.

The figure assumes demand stays steady. For seasonal items, use the demand you expect over the coming weeks rather than the historical average.

See also: Days sales of inventory calculator, Inventory-to-Sales Ratio Calculator.

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Copy this code into your page. The calculator runs in the visitor's browser and includes a link back to StockFlow.

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Frequently asked questions

How do you calculate stock cover?
Divide the stock you have on hand by your average daily demand. The result is the number of days the stock will last. Divide by 7 to get weeks of cover.
What is a good stock cover?
It depends on lead time and how critical the item is. As a rule, cover should be at least the supplier lead time plus a safety margin, and not so high that it ties up cash for slow-moving items.
What is the difference between stock cover and inventory turnover?
Stock cover looks forward: how long stock lasts at the current demand rate. Turnover looks back: how many times stock was sold and replaced over a period. They are two views of the same relationship.
Does this calculator store my data?
No. The calculation runs entirely in your browser; nothing is sent to or stored on a server.

Topic guide

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