What is Safety Stock?

Why it matters in practice

Safety stock is often set by feel, usually as a round number of weeks that someone picked once and nobody has revisited. A better way to think about it is that safety stock covers variability, not average demand. Average demand is already covered by your normal reorder quantity. What safety stock protects against is the week that sells double, or the container that clears customs ten days late. That means two products with identical sales rates can correctly carry very different buffers: a steady seller from a reliable domestic supplier needs very little, while a seasonal item shipped overseas needs a lot. The cost side is real too. Every unit of safety stock is cash sitting in a warehouse accruing storage, so the goal is not the largest buffer you can afford, it is the smallest buffer that keeps you in stock through the swings you actually see in your own history.