Free Online Stock Coverage Calculator
Calculate how many days current inventory will last.
Coverage assumes incoming stock is already available. Arrival timing is not modelled.
About the Stock Coverage Calculator
Stock coverage answers a practical question: at the current sales rate, how long will the inventory last? The calculation adds stock on hand and incoming stock, then divides by average daily sales. The result is expressed in days. If a store has 640 units on hand and 400 units on the way, and sells 22 units per day, the available total is 1,040 units, or about 47 days of coverage. That number is more useful than a raw unit count because it translates inventory into time.
The estimated stockout date projects the coverage forward from today. It uses a calendar-day estimate, so a retail calendar with closed days may need adjustment. The supplier lead time puts coverage in context. If cover is shorter than the lead time, a replenishment order may arrive too late even if the shelf still looks full. The tool flags that case as a low-coverage risk. The overstock threshold is the other side: coverage far beyond your target ties up cash and space, and may signal that demand assumptions are too optimistic or that a discontinued item needs a markdown.
The model assumes that incoming stock is available now and that daily sales are steady. Real demand varies by weekday, season, promotions, and weather, and incoming shipments can be delayed or partial. For a more careful view, run the calculation with conservative and optimistic sales rates and with the incoming shipment excluded from the total. The difference between those scenarios is the range of plausible coverage.
Unit cost is optional and only estimates the cash currently tied up in inventory. Currency formatting is local. The tool does not reserve stock for open orders, account for returns, or understand batch expiry. Use it as a quick planning check and combine it with your replenishment rules. All calculations happen in the browser.
Coverage is most useful when it is reviewed alongside sell-through and open orders. A product with months of cover may be a steady bestseller or a quiet collection of dead stock; the unit count alone cannot tell the difference. Incoming purchase orders, reserved inventory, and expiry dates can change the picture quickly. Set different thresholds for fast movers, seasonal items, and long-tail products, and review slow coverage before reordering more. A warehouse full of the wrong item is still a stockout for the customer who wanted something else.
How to use this tool
- Enter stock on hand, incoming stock, and average daily sales.
- Add your supplier lead time and an overstock threshold in days.
- Review coverage days, stockout date, inventory value, and the status flag.
- Copy the summary into an inventory or purchasing review.
Frequently asked questions
Should incoming stock be included?
Include it only if you are confident about the delivery. For a conservative view, set incoming stock to zero and compare the result.
How is the stockout date calculated?
It adds the coverage days to today's date. It assumes sales continue at the same average rate every calendar day.
What counts as overstock?
That depends on your category and cash cycle. The threshold is an input so you can set a target such as 60, 90, or 120 days.