Where; Throughput time (TH) = Work in progress (WIP) x Cycle Time (CT) Throughput time (TH) = time taken for inputs (WIP) to move through the system Work in progress (WIP) = Items in the process at one time (average) Throughput rate (1/CT) = rate at which items emerge from the system Cycle time (CT) = reciprocal of the throughput rate, time to process each item If you look in the literature, you may also see Little's Law expressed as; Where; L = W L = Length of queue (inventory/quantity/number in system = WIP) = average items arriving per unit time (also items leaving per unit time) = 1/CT W = Waiting time (average) an item spends in a queue (same as TH) I will predominantly use the first form of the equation; they are the same equation just with different symbols. While it is a simple equation, the challenge is the interpretation of problems into the appropriate variables. Discussion 1 We have a sandwich shop where an average of 60 customers arrive each hour; assuming a steady state we also have 60 customers leaving every hour. It was calculated that customers on average spend 6 minutes in the shop. How many people are in the shop at one time?