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Safety Stock Calculator
Estimate your inventory buffer from daily demand variation, fixed lead time and target service level. Free safety stock calculator with formula and example.
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Sharing is optional. WhatsApp includes your calculated result; LinkedIn shares this tool’s link. Copy the result to add it to your post.How to calculate safety stock
Safety stock = z × σd × √L
σd is the standard deviation of daily unit demand. L is a fixed lead time in days. The z factor converts a cycle service-level target into a normal-distribution buffer.
Worked example
At 95% service, daily demand deviation 5 units and lead time 14 days: 1.645 × 5 × √14 = 30.78. Round up to 31 units.
When to use this formula
This model assumes fixed lead time, independent daily demand and a reasonable normal approximation. It is less suitable for intermittent demand or correlated disruptions. Cycle service level is not the same as fill rate.
Formula reference: Read the source explanation.
What does 95% service level mean?
In this model, it targets approximately 95% of replenishment cycles without a stockout under the stated assumptions. It does not promise 95% of units supplied.
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