What Is Safety Stock – Buffer Inventory Explained

Safety stock is extra inventory you keep to avoid stockouts when demand or supply varies.

Part of our inventory management guide.

Why You Need It

Demand fluctuates. Supplier delays happen. If you order exactly what you need with zero buffer, you’ll run out when something is late or demand spikes.

How Much Safety Stock?

Depends on: demand variability, lead time variability, service level you want. Formula: Safety stock = Z × σ × √L (Z = service factor, σ = demand std dev, L = lead time). Use our Safety Stock Calculator.

Trade-Off

More safety stock = less stockout risk but more capital and storage. Less = cheaper but higher risk. Find the balance for each item.

Fast Movers

Focus safety stock on your bestsellers. Don’t over-buffer slow movers.

Stockkeeper for reorder alerts. Join the waitlist.