CMMS, EAM & Spare Parts Management worked example

Spare Parts Min Max at 90% target service-level buffer: a worked example

Here is what the math looks like when conditions slip. We hold every other input steady and drop target service-level buffer to 90%, then walk the calculation through step by step. Estimate an adjusted maximum stocking level from average parts demand, replenishment horizon, service-level buffer, and inventory accuracy.

The inputs for this scenario

  • Average spare parts demand per day: 6.5 parts / day (held at the documented default)
  • Maximum replenishment lead-time horizon: 45 cycles (held at the documented default)
  • Target service-level buffer: 90 % (the input this scenario stresses; the baseline uses 125)
  • Storeroom inventory record accuracy: 95 % (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Gross spare parts min max = average spare parts demand per day × maximum replenishment horizon.
  • Usable spare parts min max works out to 250 units at these inputs, and this is the headline figure for the scenario.
  • Gross spare parts min max works out to 293 units at these inputs.
  • Spare Parts Min Max loss from availability or service-factor limits works out to 29.25 units at these inputs.
  • Spare Parts Min Max loss from data, accuracy, or acceptance gaps works out to 13.16 units at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where target service-level buffer sits at 125% and the headline result is 347 units, this scenario comes in 28% below the baseline at 250 units.
  • The practical read: the gap between this scenario and the baseline is entirely attributable to target service-level buffer, so recovering it is worth quantifying in dollars before considering equipment or staffing changes. It assumes demand is roughly steady; for lumpy, single-failure-driven spares (large bearings, motors), a criticality and Poisson-based model will size stock better than averaged demand.

Results at a glance

  • Usable spare parts min max: 250 units (headline result)
  • Gross spare parts min max: 293 units
  • Spare Parts Min Max loss from availability or service-factor limits: 29.25 units
  • Spare Parts Min Max loss from data, accuracy, or acceptance gaps: 13.16 units

Run it with your numbers

  • To rerun this with your own numbers, open the live Spare Parts Min Max calculator, set target service-level buffer to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.