See How Many Days of Stock Cover You Actually Hold — Free
A full warehouse can still hide a product that runs out this week. Divide stock on hand by its own daily usage and compare each product’s cover with the lead time to replace it.
The proof surface
Lead-time boards date known orders. This measures what you already hold: days of cover per product against the lead time you enter, flagging anything that cannot be replaced before it runs out.
Why the flat version breaks
Averaging across products
Fast and slow movers hide each other in one total.
Using list lead times
Optimistic supplier times make every row look safe.
Treating cover as demand forecasting
This describes current stock against recent usage only.
How to work the stock cover hourglass
Enter an average daily figure from recent sales, not a forecast you hope for. Widget A sells thirty a day, so 240 units is eight days of cover.
Use the supplier’s realistic restock time including order processing. The sample is seven days; cover at or below that means the product will run out before the replacement arrives.
The summary reports the tightest product because that is where stock-out happens first. Widget B has 3.75 days of cover against a seven-day lead — flagged, and already unfixable without expedite.
Reorder, expedite or adjust promotions for flagged products. A zero daily usage makes cover undefined, so the tool rejects it rather than pretending stock lasts forever; enter a small real figure for slow movers.
What the stock cover hourglass replaces
| Question | Before | Visible working |
|---|---|---|
| Averaging across products | Fast and slow movers hide each other in one total. | Enter the lead time you can rely on |
| Using list lead times | Optimistic supplier times make every row look safe. | Read the shortest cover first |
| Treating cover as demand forecasting | This describes current stock against recent usage only. | Act on the flagged rows |
A local arithmetic aid replaces hand calculation, not expert review. No paid AI service is needed.
Run it on the samples, right here
FIRST-LOAD
Input is processed locally and a draft is saved automatically in this browser profile when storage is available. Reset to sample clears that draft; Pro history has its own clear button. A state link encodes your inputs in its URL: share only non-sensitive rows. Browser history, clipboard and anyone receiving the link may retain it. Optional AI use below leaves this device; it is not required.
Inventory arithmetic on figures you enter, not demand forecasting, accounting or a stock system. Verify counts and lead times against your own records.
Data note: Everything runs in this browser tab on the stock cover hourglass: your product | units on hand | average units sold per day stays on this device, nothing is uploaded, and the reading is rebuilt only when you press run.
Go deeper: the companion app files the same reading as a plotted bar chart sheet
The article demo above runs without limits. The companion app keeps a local history, exports the rows as CSV, prints the stock cover hourglass reading, and holds your drafts on this device — one free run, then $ 4 one-time for the layer that keeps filing.
The stock cover hourglass reading is complete for free. The optional $4 layer adds print, row CSV and the last five local reading summaries; it does not add hidden answers. Checkout is not configured yet; the article demo remains unlimited.
Open the see how many days of stock cover you actually hold companionBoundary
Inventory arithmetic on figures you enter, not demand forecasting, accounting or a stock system. Verify counts and lead times against your own records.
What this is built on
- Method: The summary reports the tightest product because that is where stock-out happens first. Widget B has 3.75 days of cover against a seven-day lead — flagged, and already unfixable without expedite.
- All sample records are invented examples. The app does not fetch measurements, policies, files or personal records.
- Google’s official pricing page, fetched 2026-09-28, lists free-tier access including AI Studio. Optional formatting only; limits and availability can change. Free-tier content may be used to improve products. Never paste private records there.
Before: Fast and slow movers hide each other in one total. After: the stock cover hourglass shows the working beside each named row so the reader can change the assumption and inspect the consequence.
Optional AI formatting, not calculation
For this stock cover hourglass, use the free AI Studio interface only if available to you, with no paid API key. Manual entry completes the same workflow for free. Supply only fictional or non-sensitive notes. Review its output against the source; never paste unresolved questions into the numeric rows.
Format my non-sensitive notes for a stock cover hourglass. Return plain rows only: product | units on hand | average units sold per day. Preserve supplied quantities exactly. Do not guess missing values; list questions separately. Do not calculate or add advice. I will check every row before pasting into the local tool.
Accepted schema: product | units on hand | average units sold per day. No AI response is executed as code.