Little's Law Calculator

About this calculator

Little's Law is a fundamental result in queueing theory stating that the average number of items in a stable system, L, equals the average arrival rate, λ, multiplied by the average time each item spends in the system, W — the elegant relationship L = λW. It holds regardless of the arrival pattern or how service time is distributed, which is what makes it so widely applicable.

This calculator takes the arrival rate and average time in system to compute L. It's used across operations management, software/systems engineering, and call center staffing — for example, to estimate how many items are sitting in a manufacturing queue, how many requests are in flight in a software system, or how many customers are typically in a store at once, just from throughput and dwell time.