Aftermarket, Field Service & Service Parts worked example

Field Failure Rate at 1.73% target field failure rate: a worked example

What does the result look like when target field failure rate reaches 1.73%? The full calculation is worked below with real intermediate numbers. a warranty or reliability manager needs to measure failures in the active installed base

The inputs for this scenario

  • Failed installed units: 128 units (unchanged)
  • Active installed units: 6,200 units (unchanged)
  • Target field failure rate: 1.73 % (raised for this scenario; the documented default is 1.5)

Working through the calculation

  • Applying the documented formula (Field failure rate = failed installed units ÷ active installed units × 100) to the inputs above produces each figure below.
  • At this operating point the engine returns 2.06 % failure rate for field failure rate, the number this scenario is built around.
  • At this operating point the engine returns -0.33 percentage points for failure-rate gap to target.
  • At this operating point the engine returns 128 units for failed installed units.
  • At this operating point the engine returns 6,200 units for active installed units.

How this compares with the baseline

  • Against the tool's baseline example, where target field failure rate sits at 1.5% and the headline result is 2.06 % failure rate, this scenario lands almost exactly on the baseline at 2.06 % failure rate.
  • A figure at this level is achievable when target field failure rate is genuinely sustained, not just peaked for a shift. It is a snapshot ratio over a chosen window and does not account for age mix, duty cycle, or units that have aged out, so it can mask early-life or wear-out patterns.

Results at a glance

  • Field failure rate: 2.06 % failure rate (headline result)
  • Failure-rate gap to target: -0.33 percentage points
  • Failed installed units: 128 units
  • Active installed units: 6,200 units

Run it with your numbers

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

Last reviewed 2026-05-12.