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Calcimator

Safety Stock Calculator

Calculate buffer inventory needed to prevent stockouts.

Inputs

units
units
days
days
%
$

Results

Safety Stock (Combined Method)

345 units

Safety Stock (Simple Method)104 units
Safety Stock Value$5,175.87
Days of Safety Coverage3.5 days
Annual Holding Cost$1,293.97
Z-Score1.65
How to Use This Calculator
  1. Enter the average daily demand and the standard deviation of daily demand.
  2. Input the average lead time in days and the standard deviation of lead time.
  3. Set the service level (e.g., 95%) to determine the Z-score.
  4. Review the recommended safety stock quantity.
  5. Higher service levels require proportionally more safety stock — balance fill rate against holding cost.

How the result changes with Average Daily Demand

Average Daily DemandSafety Stock (Combined Method)
100,000329,000 units
350,0001,151,500 units
650,0002,138,500 units
900,0002,961,000 units

What each input means

Average Daily Demand
Average daily demand in units.
Demand Std Deviation (daily)
Standard deviation of daily demand.
Average Lead Time
Average supplier lead time in days.
Lead Time Std Deviation
Standard deviation of lead time in days.
Service Level
Target service level (90, 95, 97, or 99%).
Unit Cost
Cost per unit for value calculation.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Average Daily Demand = 100, Demand Std Deviation (daily) = 20, Average Lead Time = 10, Lead Time Std Deviation = 2 = 6 input(s) provided
  2. Calculate Safety Stock
    Safety Stock
    345 = 345
  3. Calculate Safety Stock
    Safety Stock
    104 = 104
  4. Calculate Safety Stock Value
    Safety Stock Value
    5175.87 = $5,175.87

Engine last updated . Checked against 1 independently-derived test — how we verify calculators.

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