Ecommerce
Stock coverage converts units on hand into days of selling, which is the form the number is actually useful in.
Stock and demand
Units on hand right now.
Average units sold per day.
Resupply
Supplier lead time used to flag reorder-soon.
Days of Coverage
25
How many days current stock will last at the average sales rate.
Formula verified 25 September 2026
Weeks of Coverage
3.6
Days of coverage expressed in weeks.
Reorder Soon? (1 = yes)
0
Flags 1 when coverage is below the lead time you entered.
Estimate only — platform fees and costs vary; verify current rates. Read the full disclaimer ↓
Where your computed days of coverage falls, judged against the supplier lead time you entered. The danger line is the lead time itself — once coverage drops to or below it, an order must already be on its way. Bands are guides, not rules; a demand surge shortens real coverage.
| Days of coverage | What it usually means | |
|---|---|---|
| Below lead time | Urgent — stock runs out before a fresh order could arrive; reorder now or risk a stockout. | |
| 1× to 2× lead time | Getting low — enough to cover one replenishment cycle with little slack; line up the next order. | ◀ your result (25 days) |
| 2× to 4× lead time | Comfortable — a healthy runway above the lead time for most products. | |
| Above 4× lead time | Well stocked, possibly overstocked — capital and space may be tied up in slow-moving cover. |
Estimates only — not financial, tax, or professional advice.
Calculated in your browser — the numbers you enter are never sent to our servers.
What it calculates: Days of Coverage, Weeks of Coverage, Reorder Soon? (1 = yes).
Updated 25 September 2026 · 4,367 automated cases pass
A raw stock count is not comparable across products. Five hundred units of something selling 40 a day is twelve days of cover; five hundred units of something selling two a day is eight months of dead capital.
Converting to days puts every line on the same scale, which is what makes a stock list reviewable at a glance instead of item by item.
The comparison that matters is coverage versus lead time. If you hold 8 days of stock and resupply takes 14, the stockout is already determined — the order you place today arrives six days after the shelf empties.
That is why lead time is an input here rather than something to check separately. The gap between the two numbers is the warning, and it appears long before the stock actually runs out.
Low coverage risks lost sales; high coverage ties up money, fills storage and ages the stock toward markdown. Many businesses watch only the low end and quietly accumulate lines with a year of cover.
A practical review sorts by coverage in both directions: anything below lead time needs ordering now, and anything far above needs promoting, discounting or not reordering.
Coverage is only as good as the demand rate. Using a rate computed across a promotional spike overstates demand and makes coverage look dangerously thin; using an off-season rate does the opposite.
For seasonal products, compute demand from the period you are heading into rather than the one you just left. The arithmetic is trivial; choosing the right denominator is the actual work.
Days of coverage is how long your on-hand stock will last at the current sales rate before it runs out. It is a fast indicator of whether you are well stocked, getting low, or overstocked relative to how quickly you sell.
Coverage looks forward from today, estimating how many days stock will last. Turnover looks back over a period, counting how many times you sold and replaced inventory. One is a snapshot; the other is a frequency over time.
Reorder when days of coverage fall to or below your supplier lead time, since that is when a new order must be placed to arrive before you run out. This calculator flags that condition for you using the lead time you enter.
Often, yes. Very high coverage ties up cash and storage space and raises the risk of obsolescence, especially for fast-changing products. The right level balances availability against the cost of holding inventory.
This tool measures coverage from on-hand stock only. If you want to include stock already on its way, add expected receipts to current stock, but remember those units are not sellable until they arrive.
Coverage moves as both stock and sales change. Selling faster shortens it, restocking lengthens it. Because it is a forward estimate built on an average, it should be rechecked regularly rather than treated as a fixed number.
Figures on this page are checked against primary, authoritative sources. Links open in a new tab.
What the calculation assumes
Where it stops
Business disclaimer
Results are estimates for planning and analysis based on the figures you enter. They are not accounting, tax, or financial advice — verify with your own records and a qualified professional before making decisions.
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Part of Financial Ratios — 14 calculators, with which one answers which question.
Published 13 September 2026