Safety Stock Calculator
Safety stock and reorder point from service level, demand variability and lead-time variability.
Inputs
units/day
units
days
days
Results
- Safety stock
- 344 units
- Reorder point
- 1,244 units
- Lead-time demand
- 900 units
Formula
SS = Z × √(LT × σd² + d̄² × σLT²)
Reorder point = d̄ × LT + SS
Assumptions & limits
- Demand and lead time are independent and roughly normal.
- Set lead-time deviation to 0 for reliable suppliers (SS = Z × σd × √LT).
Worked example
√(9 × 400 + 10,000 × 4) = √43,600 = 208.8 × 1.6449 = 343.5 → 344 units; ROP = 900 + 344 = 1,244.