NON-SEASON (Regular):
Lead Time + Safety Stock = Reorder Point
Reorder Point + Days Supply (or Order Cycle) = Preferred Stocking Level
- Order Cycle is defined as a global value (I don’t think we call it Order Cycle but that’s the standard nomenclature in WD) represented in terms of # of days supply. Think about this as how often do you want to be placing PO’s or how many turns are you trying to achieve.
So, Reorder Point is 28 (7 x 4) + 12 (3 x 4) = 40 units.
Preferred Stocking Level is 40 + 240 (4 x 60) = 280
This is a very standard, yet simplistic way of identifying re-order points and stocking levels (we don’t handle lost sales, exceptional sales or backorder tolerance thresholds) but that’s the formula.
SEASON:
The formula is the same, but the difference is the audit period. Instead of counting back the last 60 days of sales to identify our daily demand rate, we instead go back 1 year from today (or whatever day the computer performs the forecast) and count FORWARD 60 days. Those 60 days become the audit period and then we calculate everything else based on the historical consumption during that audit period. Why do we do this? Because we want to see what our demand was – on this seasonal item – LAST SEASON. Counting back the last 60 days from today is irrelevant to seasonality that comes and goes every 3 months.