# Little's law applied to an IT department

> Little's law links work in progress, throughput, and lead time: too many parallel projects mechanically lengthen deadlines. Formula, worked example, and IT applications.

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## What does Little's law say and how does it apply to an IT department?

Little's law states that, in a stable system, work in progress equals throughput multiplied by average lead time (WIP = throughput × lead time). For an IT department with constant throughput, doubling the number of parallel projects therefore doubles each project's average lead time: limiting work in progress is the most direct way to shorten deadlines.

## Formula

- Work in progress = throughput × average lead time.

- Average lead time = work in progress ÷ throughput.

- Assumption: stable system, constant average throughput over the period.

## Worked example

A team completes an average of 2 projects per month. With 6 projects in parallel, the average lead time is 6 ÷ 2 = 3 months. With 12 projects in parallel and the same throughput, it rises to 6 months. Opening more projects did not increase what the team finishes; it only lengthened each one's wait.

## IT applications

- Limit the number of active projects per team instead of accepting every request.

- Use net capacity to decide how many projects to start.

- Arbitrate in committee by accepting a project only if another finishes or is postponed.

## FAQ

### Does Little's law apply to uneven projects?

Yes, in averages over a stable period. It gives an order of magnitude, not an exact forecast project by project.

### How do you measure an IT department's throughput?

By counting projects, or deliverables, completed per month over several months.

### Is this an argument to refuse projects?

It is an argument to sequence them: starting fewer projects at a time finishes them sooner.

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