Compare assumptions before changing a stock rule
Use this tool for a small, explicit what-if comparison for one stock item. Enter the same inventory snapshot for both scenarios, then change expected daily demand, supplier lead time or the extra buffer days. The result shows how those assumptions affect the threshold. It does not forecast sales or choose the right assumptions for your business.
Understand the three stock quantities
On-hand units are physically present. Committed units are already allocated; subtract them to find net uncommitted on-hand stock. Incoming units are the units you decide to include from expected deliveries. Inventory position here is on-hand plus incoming minus committed. An incoming delivery contributes to this position but is not treated as physically usable today.
Do not count the same commitment or incoming shipment twice. If your source system already reports available stock after allocations, adapt the inputs so commitments are subtracted only once. The app has no connection to your inventory system and cannot verify purchase orders, delivery timing, damaged stock or backorders. If commitments exceed on-hand, the negative net quantity is shown rather than hidden.
How the comparison works
For each scenario, lead-time demand equals daily demand multiplied by lead-time days. The extra buffer is daily demand multiplied by your chosen buffer days. Their sum is the model’s reorder threshold: daily demand × (lead time + buffer days). The table compares the same inventory position with each threshold and shows any shortfall or excess.
The buffer is a chosen number of days in this model. It is not a statistically calculated safety stock or a service-level guarantee. A position at or below the threshold is labelled for review, not converted into an automatic purchase order. The threshold shortfall is not a recommended order quantity; ordering quantity also depends on target coverage, minimum order sizes, existing orders and other constraints outside this tool.
Walk through the example
With 80 units on hand, 20 incoming and 10 committed, inventory position is 90 and net uncommitted on-hand is 70. Scenario A uses 12 units per day, seven lead-time days and three buffer days. Its threshold is 120 units, leaving the position 30 below that threshold.
Scenario B uses 15 units per day, ten lead-time days and three buffer days. Its threshold becomes 195, or 75 more than A. The same position is 105 below it. Physical stock cover is about 5.83 days in A and 4.67 in B. These cover figures exclude incoming deliveries because their arrival schedule has not been provided.
Read stock cover carefully
Physical cover divides positive net uncommitted on-hand units by the stated daily demand. Negative net stock is reported separately and contributes zero physical cover. Zero daily demand produces no depletion estimate rather than an infinite number. No particular calendar date is predicted.
Use calendar or working days consistently across demand, lead time and buffer. This app does not interpret weekends, holidays, staggered receipts or within-day arrival times. A stock position can look sufficient while a late delivery still causes a shortage before it arrives. Review actual timing separately; the app does not simulate an incoming-delivery schedule.
Limits and temporary inputs
All outputs use a constant demand assumption and are rounded for display to two decimal places. The interface permits fractional units for materials measured continuously; it does not round up to a pack or whole-item purchase. Numeric bounds are interface limits, not recommended operating ranges.
Seasonal demand, promotions, uncertain lead times, multiple locations, expiry, substitutes, lost sales, costs and statistical stockout probabilities are outside this comparison. Keep a separate record if you need to retain assumptions. Editing a field clears the old result so you can recalculate an updated snapshot.
Reference: inFlow’s explanation of reorder points.