ERP & MRP Planning worked example

Supplier Lead Time Buffer with usable buffer inventory of 11,300 units: a worked example in erp & mrp planning

Push usable buffer inventory up to 11,300 units and the picture changes. This example computes every intermediate figure at that operating point. a materials manager needs to know whether buffer stock covers supplier risk

The inputs for this scenario

  • Usable buffer inventory: 11,300 units (raised for this scenario; the documented default is 4,500)
  • Average daily usage: 300 units / day (unchanged)
  • Supplier risk multiplier: 1.25 x (unchanged)

Working through the calculation

  • Applying the documented formula (Protected supplier buffer days = usable buffer inventory ÷ average daily usage ÷ supplier risk multiplier) to the inputs above produces each figure below.
  • At this operating point the engine returns 30.13 days for protected supplier buffer days, the number this scenario is built around.
  • At this operating point the engine returns 37.67 days for unadjusted supplier buffer days.
  • At this operating point the engine returns 11,300 units for usable buffer inventory.
  • At this operating point the engine returns 300 units / day for average daily usage.

How this compares with the baseline

  • Against the tool's baseline example, where usable buffer inventory sits at 4,500 units and the headline result is 12 days, this scenario comes in 151% above the baseline at 30.13 days.
  • It converts usable buffer inventory and average daily usage into protected buffer days, then discounts them by a supplier risk multiplier. The value of this scenario is the size of the gap it exposes: that gap, priced out over a year, is the budget you can justify spending to close it.

Results at a glance

  • Protected supplier buffer days: 30.13 days (headline result)
  • Unadjusted supplier buffer days: 37.67 days
  • Usable buffer inventory: 11,300 units
  • Average daily usage: 300 units / day

Run it with your numbers

  • Every input above is editable in the live Supplier Lead Time Buffer calculator, which recalculates instantly and can be shared with the inputs intact.

Last reviewed 2026-05-12.