Kanban: Definition of Lead Time and Cycle Time

Important: Cycle time as a concept can have multiple meanings. This blog post uses just one specific meaning. Alexei Zheglov has a more accurate discussion of the cycle time concept.

When doing Kanban for software development measuring cycle and lead times is important but often the terms are confused or defined in a fuzzy way. Here is a useful definition from the „Lean and Kanban“ blog:

Lead time clock starts when the request is made and ends at delivery. Cycle time clock starts when work begins on the request and ends when the item is ready for delivery. Cycle time is a more mechanical measure of process capability. Lead time is what the customer sees.

Let’s have a closer look and let’s assume we are working with Kanban in a maintenance team. Bugs are reported via tickets in a ticket system like Bugzilla, Jira or Mantis. When the bug is detected a ticket is created and when the bugfix is live, the ticket is closed. This whole period of time is the lead time. The lead time is the time and not the effort. You may have a lead time of 100 days and only have to work 1 hour to fix the bug. Sometime you start working on the bug. The cycle time is the time from the start of the work until the bugfix is live. Again the cycle time is not the effort. Lead time can’t be shorter than cycle time. Often lead time is a lot longer. In the context of maintenance there is often a SLA (Service Level Agreement) in place that defines in which time frame you have to fix a bug. Often the SLA defines a resolution time. That is the same as the lead time: Most SLAs also define a response time. That is the time available until the team has to respond to a new bug ticket: is it really a bug and what is the priority. With these definitions in place it is obvious that the lead time is what is relevant from the business perspective. The cycle time is what the team can influence by itself by changing its work process. To reduce lead times one can (and should) reduce cycle time. But often the time before the work starts is really long so this wait time should be reduced also.