ERP & MRP Planning worked example

Supplier Lead Time Buffer with usable buffer inventory of 2,300 units: a worked example in erp & mrp planning

This worked example runs the supplier lead time buffer numbers for a tougher week than the baseline: usable buffer inventory of 2,300 units instead of the typical 4,500 units. Estimate protected days of supply from available buffer stock, daily usage, and supplier risk multiplier.

The inputs for this scenario

  • Usable buffer inventory: 2,300 units (the input this scenario stresses; the baseline uses 4,500)
  • Average daily usage: 300 units / day (held at the documented default)
  • Supplier risk multiplier: 1.25 x (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Protected supplier buffer days = usable buffer inventory ÷ average daily usage ÷ supplier risk multiplier.
  • Protected supplier buffer days works out to 6.13 days at these inputs, and this is the headline figure for the scenario.
  • Unadjusted supplier buffer days works out to 7.67 days at these inputs.
  • Usable buffer inventory works out to 2,300 units at these inputs.
  • Average daily usage works out to 300 units / day at these inputs.

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 48.89% below the baseline at 6.13 days.
  • Use it when sizing safety stock for a purchased part or deciding whether current buffer covers a supplier's expected lead time and variability. A result at this level usually justifies acting on the stressed input before touching anything else, because every other figure in the table is downstream of it.

Results at a glance

  • Protected supplier buffer days: 6.13 days (headline result)
  • Unadjusted supplier buffer days: 7.67 days
  • Usable buffer inventory: 2,300 units
  • Average daily usage: 300 units / day

Run it with your numbers

  • To rerun this with your own numbers, open the live Supplier Lead Time Buffer calculator, set usable buffer inventory to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.