# Case: Lead Time Demand >= S

When the `lead time demand`

is greater than or equal to the `initial stocking level (S)`

the formula for approximating expected average inventory level is:

`initialStockingLevel / (leadTimeDemand+1); `

The reason we add to 1 `leadTimeDemand`

in the denominator to cover the
edge case where both the `initialStockingLevel`

and the `leadTimeDemand`

are
1.

In this case, the expected average inventory level is 1/2.

# Case: Lead Time Demand < S

`(initialStockingLevel - leadTimeDemand) + 0.5; `