Outdoor Power Equipment worked example

Field Service Parts Buffer with service part daily usage of 100 parts / day: a worked example

What does the result look like when service part daily usage reaches 100 parts / day? The full calculation is worked below with real intermediate numbers. a service parts or aftermarket team needs to size stock for fast-moving spares without stocking out during season

The inputs for this scenario

  • Service part daily usage: 100 parts / day (raised for this scenario; the documented default is 40)
  • Replenishment lead time: 21 days (unchanged)
  • Service parts safety stock: 120 parts (unchanged)

Working through the calculation

  • Applying the documented formula (Lead-time demand = service part daily usage × replenishment lead time) to the inputs above produces each figure below.
  • At this operating point the engine returns 0.04 units for protected days of supply, the number this scenario is built around.
  • At this operating point the engine returns 4.76 days for unprotected days.
  • At this operating point the engine returns 100 pieces for inventory.
  • At this operating point the engine returns 21 pieces / day for daily usage.

How this compares with the baseline

  • Against the tool's baseline example, where service part daily usage sits at 40 parts / day and the headline result is 0.02 units, this scenario comes in 150% above the baseline at 0.04 units.
  • A figure at this level is achievable when service part daily usage is genuinely sustained, not just peaked for a shift. It assumes steady daily usage; for parts with spiky, weather-driven demand the average understates peak needs, so the safety stock term has to absorb that variability.

Results at a glance

  • Protected days of supply: 0.04 units (headline result)
  • Unprotected days: 4.76 days
  • Inventory: 100 pieces
  • Daily usage: 21 pieces / day

Run it with your numbers

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

Last reviewed 2026-05-12.