How to use this calculator
Choose a method and enter demand and lead-time observations or assumptions.
Formula and method
Peak buffer=max(0, maximum daily demand × maximum lead time − average daily demand × average lead time). Normal buffer=z√(Lσd²+d²σL²).
Worked example
Peak: 30×10−20×7=160 units. Service: z=1.645, σd=4, σL=1, L=7, d=20 gives about 37.222 units.
Assumptions and supported scope
Service approximation depends on independence and normality; z is user supplied. Do not interpret the peak method as a service guarantee.
Method references
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