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Little Law For Factory Calculator

Work out little law for factory instantly with clear inputs, formula shown and shareable results.

About Little Law For Factory Calculator

Little's law states that in any stable process, work in process equals throughput times flow time. Knowing any two of the three gives the third, which makes it the most useful single relationship in factory and queue analysis. It holds regardless of the distribution of arrival or service times.

Formula

Little's law

WIP = throughput x lead time; lead time = WIP / throughput; throughput = WIP / lead time

Worked example

With the default values below, Little Law For Factory Calculator returns Calculated Quantity of 4.0000. Change any input above and every figure here is recalculated in your browser.

Inputs used

Quantity To Findone of Lead time, WIP, Throughput
Lead time
Work In Processminimum 0.01 units
480 units
Throughputminimum 0.01 units/hour
120 units/hour
Lead Timeminimum 0.01 hours
4 hours

Results

Calculated Quantity
4.0000
Work In Process
480.000
Throughput
120.000
Lead Time
4.0000

Step by step

  1. 1Values used
  2. 2Little's law
  3. 3Calculated Quantity= 4.0000
  4. 4Work In Process= 480.000
  5. 5Throughput= 120.000
  6. 6Lead Time= 4.0000

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

What does stable mean here?

Average input equals average output over the measurement window, with no systematic build-up or drain of inventory. Over a long enough period almost every real process qualifies.

Does it apply to service processes?

Yes — jobs in a queue, tickets in a support system, patients in a clinic. Units and time just need to be consistent.

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