Safety Stock
Calculator
Results
- Safety stock (units)
- 200.051868
- Lead-time demand standard deviation
- 121.243556
Results
| Safety stock (units) | 200.051868 |
| Lead-time demand standard deviation | 121.243556 |
formula-map diagram
- Safety stock (units)
- 200.051868
- Lead-time demand standard deviation
- 121.243556
Diagram
Formula
Safety stock = z × σ_demand × √(lead time)= 200.05186827421
Note
This is a simplified model using standard logistics formulas; real-world contracts, carrier rules, and regulations may add further terms.
More in Logistics and shipping
See all →Frequently asked questions
What is safety stock and what does this calculator find?+
Safety stock is the extra buffer inventory kept on hand to guard against unexpected demand spikes or supply delays, beyond what you'd need if demand and lead time were perfectly predictable.
What inputs are commonly required?+
Average daily demand, demand variability, average lead time, lead time variability, and a desired service level (how often you want to avoid stockouts) — more advanced formulas use all of these together.
What's a simple formula this might use?+
A basic version is: Safety Stock = (Maximum daily demand × Maximum lead time) − (Average daily demand × Average lead time). More statistically rigorous versions incorporate demand and lead-time standard deviations with a service-level factor.
Why does higher desired service level require disproportionately more safety stock?+
Because demand and lead time variability typically follow something close to a normal distribution, pushing your protection from, say, 95% to 99% service level requires a much larger safety margin than going from 80% to 95% — the relationship isn't linear.
What happens if I set safety stock too low or too high?+
Too low risks frequent stockouts and lost sales; too high ties up cash in excess inventory and increases storage costs. Safety stock is a balance point, not a number to simply maximize.