Procurement reorder lead-time buffer calculator

Calculate empirical reorder demand and mean observed demand with your own figures.

Your numbers

Use the units shown. Results update as you change valid inputs.

Use empirical reorder demand and mean observed demand to compare changes to your inputs. The method and limits below explain the scope.

Examples

Examples

Try the starting example

Observed lead-time demand scenarios (inventory units)
20,25,30,40,50
Desired empirical coverage quantile (0<q≤1)
0.8
Empirical reorder demand (units)
40
Mean observed demand (units)
33
Buffer above mean (units)
7

Try another scenario

Observed lead-time demand scenarios (inventory units)
20,25,30,40,50
Desired empirical coverage quantile (0<q≤1)
1
Empirical reorder demand (units)
50
Mean observed demand (units)
33
Buffer above mean (units)
17
Calculation method

Calculation method

Empirical reorder demand (units)

Sorted observation at rank ceil(q×n), with ranks starting at one.

Mean observed demand (units)

Arithmetic mean of supplied scenarios.

Buffer above mean (units)

max(0,empirical reorder demand − mean).

Symbols and units
a
Observed lead-time demand scenarios (inventory units)
b
Desired empirical coverage quantile (0<q≤1)

Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.

Assumptions & limits

Assumptions & limits

  • Empirical nearest-rank coverage across observed lead-time-demand scenarios; no normality assumption or future service guarantee. Supported limits: Nonempty finite nonnegative scenarios. Quantile strictly positive and ≤1.
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