Lean Manufacturing & Operations worked example

Lead Time from WIP (Little's Law) with total work-in-process inventory of 100 units: a worked example

This worked example runs the lead time from wip (little's law) numbers for a tougher week than the baseline: total work-in-process inventory of 100 units instead of the typical 200 units. Calculate manufacturing lead time from WIP and throughput using Little's Law: Lead Time = WIP / Throughput.

The inputs for this scenario

  • Total work-in-process inventory: 100 units (the input this scenario stresses; the baseline uses 200)
  • Line throughput rate: 50 units/day (held at the documented default)
  • Time-unit conversion factor: 1 x (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Lead Time = WIP / Throughput x Conversion Factor.
  • Manufacturing lead time works out to 2 days at these inputs, and this is the headline figure for the scenario.
  • Raw ratio works out to 2 value at these inputs.
  • Conversion factor works out to 1 x at these inputs.
  • Throughput rate works out to 50 value at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where total work-in-process inventory sits at 200 units and the headline result is 4 days, this scenario comes in 50% below the baseline at 2 days.
  • Use it to predict or sanity-check lead time from a WIP count and a known throughput, or to show how cutting WIP shortens lead time. A result at this level usually justifies acting on the stressed input before touching anything else, because every other figure in the table is downstream of it.

Results at a glance

  • Manufacturing lead time: 2 days (headline result)
  • Raw ratio: 2 value
  • Conversion factor: 1 x
  • Throughput rate: 50 value

Run it with your numbers

  • To rerun this with your own numbers, open the live Lead Time from WIP (Little's Law) calculator, set total work-in-process inventory to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.