Safety Stock Calculator
Estimate demand-variability safety stock, buffer days and an inventory position for reordering.
This tool runs entirely in your browser. Your files are never uploaded to a server.
24.75
Safety stock
180
Lead-time demand
204.75
Reorder inventory position
1.24
Buffer days
What this calculator shows
This calculator estimates a statistical inventory buffer for uncertain daily demand during a stated average replenishment lead time and service objective.
How to use it
Enter average daily demand, the standard deviation of daily demand, average lead time in days and a Z service factor that matches the desired availability level.
Calculation method
Safety stock equals service factor times daily-demand standard deviation times the square root of lead time; lead-time demand is then added for the inventory position.
Worked planning example
This calculator estimates a statistical inventory buffer for uncertain daily demand during a stated average replenishment lead time and service objective. Safety stock equals service factor times daily-demand standard deviation times the square root of lead time; lead-time demand is then added for the inventory position.
How to read the result
Enter average daily demand, the standard deviation of daily demand, average lead time in days and a Z service factor that matches the desired availability level. Safety stock equals service factor times daily-demand standard deviation times the square root of lead time; lead-time demand is then added for the inventory position.
Planning limitations
The model assumes independent demand variation and a stable average lead time; seasonality, correlated demand, supplier variability and review cadence require a richer policy.
Privacy and next steps
The model assumes independent demand variation and a stable average lead time; seasonality, correlated demand, supplier variability and review cadence require a richer policy. The calculation runs locally in the browser and entered operational values are not uploaded.
Frequently Asked Questions
- How is the result calculated?
- Safety stock equals service factor times daily-demand standard deviation times the square root of lead time; lead-time demand is then added for the inventory position.
- Which inputs are required?
- Enter average daily demand, the standard deviation of daily demand, average lead time in days and a Z service factor that matches the desired availability level.
- What are the limitations?
- The model assumes independent demand variation and a stable average lead time; seasonality, correlated demand, supplier variability and review cadence require a richer policy.
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