Little's Law Calculator
Solve Little's Law for any one of WIP, throughput or lead time — the fundamental relationship behind production flow. Free, instant and fully in your browser.
WIP (units)
100
units of work in process
WIP = Throughput × Lead time (L = λ × W)
Keep your time units consistent: if throughput is units/hour, lead time must be in hours.
What is Little's Law?
Little's Law states that the average work in process (WIP) equals throughput multiplied by lead time (L = λ × W). It is a fundamental, assumption-light law of flow: cut WIP or raise throughput and lead time falls. It links inventory, flow rate and time, and underpins pull systems, kanban sizing and lead-time reduction.
How to use Little's Law
- 1
Pick the unknown
Choose whether you want WIP, throughput or lead time.
- 2
Enter the other two
Provide the two known values, keeping time units consistent.
- 3
Read the result
The tool applies L = λ × W to solve for the missing value instantly.
Frequently asked questions
What does Little's Law assume?
It holds for a stable system over a long enough period — arrivals and departures roughly balance and WIP is not trending. It does not require any particular distribution, which is why it is so widely applicable.
How does Little's Law help reduce lead time?
Since lead time = WIP / throughput, the fastest lever for shorter lead time is usually less WIP. Pull systems and kanban limit WIP precisely to exploit this.
How is this related to kanban and pull?
Kanban caps WIP, which by Little's Law caps lead time for a given throughput. Yamazo Studio's standard work and balancing keep throughput stable so reduced WIP translates into shorter, predictable lead time.
Related lean tools & guides
Flow is measured, then improved
The law explains flow. Yamazo Studio turns shop-floor video into the standard work, balancing and waste analysis that make flow real — one offline Lean Operating Desk.
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