Inventory Management Blog
Expert perspectives on inventory, supply chain and operational excellence to help your business work smarter,
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Safety Stock: How Much Inventory Should Your Business Really Hold?
Safety stock protects a business against uncertainty.
The challenge is determining how much protection is actually required.
Too little safety stock can increase stockouts. Too much can unnecessarily tie up working capital. Safety stock should be treated as a deliberate business decision rather than simply extra inventory. The right buffer reflects the commercial risk of being unavailable while avoiding unnecessary investment in stock that may never be required.
What should safety stock protect against?
Primarily two uncertainties:
Demand variability — actual demand differs from expected demand.
Lead-time variability — suppliers take longer or shorter than expected to deliver.
If both are stable, less protection may be required. If either is highly variable, the inventory policy needs to account for that risk.
Why rules of thumb cause problems
Some organisations use the same number of days or weeks of safety stock for every product.
That is simple, but it ignores differences in:
- demand variability;
- supplier reliability;
- lead time;
- product importance;
- service-level requirements.
A fast-moving critical SKU supplied by an unreliable vendor should not necessarily use the same policy as a predictable low-priority item.
Review safety stock dynamically
Safety-stock parameters should not be set once and forgotten.
Demand patterns change. Suppliers change. Lead times change. Products mature.
Review the parameters periodically and particularly after significant changes in demand or supply performance.
Free Inventory Health Check
Do your safety-stock policies reflect actual demand and supplier behaviour? Find out with the Free Inventory Health Check.