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How much buffer does daily demand variation imply?
Model a normal-approximation safety stock under fixed lead time and independent daily demand.
Example scenario
Editable demonstration inputs, not verified industry benchmarks. Enable JavaScript to calculate your own scenario.
- Average daily demand
- 200
- Standard deviation of daily demand
- 60
- Fixed replenishment lead time
- 15 days
- Chosen service z-score
- 1.645 ×
- Inventory cash cost / unit
- $30
Modeled safety-stock units
Example result only, not a forecast or promise.
- Safety-stock cash investment
- $11,468
- Reorder point units
- 3,383
- Average demand during lead time
- 3,000
What to do with this result
Check lead-time variability and demand autocorrelation; choose a z-score deliberately rather than equating cycle service with fill rate.
Know what is inside the model.
Planning model, not personalized financial advice. Your inputs remain in your browser.
Calculation method
Safety stock = z × daily demand standard deviation × sqrt(lead-time days). Reorder point = mean daily demand × lead time + safety stock.
Assumptions and limitations
- Example inputs are editable scenarios, not Aryo results or independently verified industry benchmarks.
- Demand, lead times and service levels are scenario inputs. Validate variability, physical constraints and supplier terms before ordering.
- Fixed lead time, independent daily demand and a normal approximation. z = 1.645 is an example choice, not a recommended service target.