Convert safety inventory into days of demand coverage and compare that buffer with a possible replenishment delay. This calculator helps planners see how long the safety stock can sustain average demand, when it would run out, and whether the entered delay scenario leaves a surplus or shortage.
Coverage days is the time the usable safety buffer can support average demand after ordinary replenishment stock is exhausted. It represents protection time, not the supplier’s normal lead time.
Demand can vary from the average. For volatile items, test a higher daily demand or lower availability factor rather than treating the estimate as a guarantee.
With 600 safety units, demand of 120 units per day, a 4-day delay, and 95% availability, usable buffer is 570 units. It covers 4.75 days and leaves 90 units after the delay.
No. Here it means the number of delay days the usable safety buffer can cover at average demand.
It allows for damaged, quarantined, misplaced, or otherwise unusable units in the recorded buffer.
Expected delay demand exceeds usable safety inventory, indicating a projected unit shortage under that scenario.
Yes. Replace average daily demand with the higher demand rate you want to stress-test.
Not necessarily. Coverage refers to the period after normal working inventory is exhausted and the safety buffer is being consumed.
| Input | Unit | Role |
|---|---|---|
| Safety inventory on hand | units | Units reserved as the replenishment buffer. |
| Average daily demand | units/day | Expected daily consumption during a delay. |
| Possible supplier delay | days | Delay beyond the normal planned lead time. |
| Availability factor | % | Share of recorded buffer units expected to be usable. |