NPI, DFM/DFA & Engineering Change worked example

Launch Inventory Buffer with on-hand launch inventory of 3,000 units: a worked example in npi, dfm/dfa & engineering change

Push on-hand launch inventory up to 3,000 units and the picture changes. This example computes every intermediate figure at that operating point. Use it when launch inventory buffer in npi, dfm/dfa and engineering change is being sized for a buffer or safety stock review.

The inputs for this scenario

  • On-hand launch inventory: 3,000 units (raised for this scenario; the documented default is 1,200)
  • Forecast daily usage at launch: 85 units / day (unchanged)
  • Launch safety-stock factor: 1.1 units (unchanged)

Working through the calculation

  • Applying the documented formula (Launch inventory buffer cycle stock = launch inventory buffer daily usage × launch inventory buffer lead time) to the inputs above produces each figure below.
  • At this operating point the engine returns 32.09 days for protected days of supply, the number this scenario is built around.
  • At this operating point the engine returns 35.29 days for unprotected days.
  • At this operating point the engine returns 3,000 pieces for inventory.
  • At this operating point the engine returns 85 pieces / day for daily usage.

How this compares with the baseline

  • Against the tool's baseline example, where on-hand launch inventory sits at 1,200 units and the headline result is 12.83 days, this scenario comes in 150% above the baseline at 32.09 days.
  • It converts on-hand launch inventory into days of supply at the forecast usage rate and compares protected against unprotected coverage. 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 days of supply: 32.09 days (headline result)
  • Unprotected days: 35.29 days
  • Inventory: 3,000 pieces
  • Daily usage: 85 pieces / day

Run it with your numbers

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

Last reviewed 2026-05-12.