Cycle time

Cycle time is the total elapsed time to complete one unit of work, measured from the moment active processing starts until the unit is finished and ready for the next step. In manufacturing this might be the time to assemble one product on a line; in a service process it might be the time to resolve one support ticket once an agent picks it up.

It differs from lead time, which starts earlier — when a customer places an order or a task enters a queue — and includes any waiting time before work begins; cycle time only counts active processing. A common way to estimate it, drawn from Little's law, is cycle time = work in process / throughput: with 20 units in progress and 4 completed per hour, average cycle time is 5 hours. Reducing cycle time without adding capacity usually means raising throughput or removing a bottleneck.

Practitioners track cycle time to find where a process is slow, to set realistic delivery commitments, and to measure whether a process change actually helped. A common pitfall is averaging cycle times across very different task types, which hides the variation that actually causes delays; tracking the distribution, not just the mean, is usually more useful for diagnosing problems and is central to Six Sigma improvement work.