Lean Manufacturing & Operations worked example

Little's Law WIP Calculator with throughput rate of 25 units/day: a worked example

Here is what the math looks like when conditions slip. We hold every other input steady and drop throughput rate to 25 units/day, then walk the calculation through step by step. Apply Little's Law to calculate steady-state WIP from throughput rate and average lead time: WIP = Throughput x Lead Time.

The inputs for this scenario

  • Throughput rate: 25 units/day (the input this scenario stresses; the baseline uses 50)
  • Average lead time: 4 days (held at the documented default)
  • Adjustment factor: 1 x (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: WIP = Throughput x Lead Time x Adjustment Factor.
  • Predicted WIP level (units) works out to 100 units at these inputs, and this is the headline figure for the scenario.
  • Base product works out to 100 value at these inputs.
  • Multiplier works out to 1 x at these inputs.
  • Factor A x B works out to 100 value at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where throughput rate sits at 50 units/day and the headline result is 200 units, this scenario comes in 50% below the baseline at 100 units.
  • The practical read: the gap between this scenario and the baseline is entirely attributable to throughput rate, so recovering it is worth quantifying in dollars before considering equipment or staffing changes. Little's Law holds only for a stable system where arrival and departure rates are balanced over the window; during ramp-up, ramp-down, or a sustained bottleneck it will mispredict because WIP is still changing.

Results at a glance

  • Predicted WIP level (units): 100 units (headline result)
  • Base product: 100 value
  • Multiplier: 1 x
  • Factor A x B: 100 value

Run it with your numbers

  • To rerun this with your own numbers, open the live Little's Law WIP Calculator calculator, set throughput rate to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.