Aftermarket, Field Service & Service Parts worked example

Service Parts Forecast Accuracy at 99% target forecast accuracy: a worked example

This scenario runs the service parts forecast accuracy calculation on the strong side: 99% target forecast accuracy, with every other input held at its documented default. a parts inventory analyst needs to evaluate whether service-parts forecasts are reliable enough for stocking decisions

The inputs for this scenario

  • Correctly forecast service part demand: 1,120 parts (unchanged)
  • Actual service part demand: 1,280 parts (unchanged)
  • Target forecast accuracy: 99 % (raised for this scenario; the documented default is 88)

Working through the calculation

  • Applying the documented formula (Forecast accuracy = correctly forecast demand ÷ actual service part demand × 100) to the inputs above produces each figure below.
  • At this operating point the engine returns 87.5 % forecast accuracy for service parts forecast accuracy, the number this scenario is built around.
  • At this operating point the engine returns 11.5 percentage points for forecast accuracy gap.
  • At this operating point the engine returns 1,120 parts for correctly forecast demand.
  • At this operating point the engine returns 1,280 parts for actual service part demand.

How this compares with the baseline

  • Against the tool's baseline example, where target forecast accuracy sits at 88% and the headline result is 87.5 % forecast accuracy, this scenario lands almost exactly on the baseline at 87.5 % forecast accuracy.
  • Use it at each planning cycle close to grade last period's spare-parts forecast and decide whether to retune your model or safety stock. Treat this as a target state: the delta against the baseline quantifies what the improvement is worth before you commit to chasing it.

Results at a glance

  • Service parts forecast accuracy: 87.5 % forecast accuracy (headline result)
  • Forecast accuracy gap: 11.5 percentage points
  • Correctly forecast demand: 1,120 parts
  • Actual service part demand: 1,280 parts

Run it with your numbers

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

Last reviewed 2026-05-12.