Cycle Time (CT) is how long the value-adding work on a stage takes. Wait Time (WT) is how long the work sits idle before or after the stage - queued, in transit, awaiting approval, waiting for parts.
Why they're separate
Because they behave completely differently. Cycle time is a machine or human capability problem - you speed it up with better tools, better ergonomics, or better skill. Wait time is a system-level problem - you attack it with smaller batches, capacity balancing, and elimination of hand-offs.
What the ratio tells you
In most processes, wait time is 5x to 20x cycle time. If you're seeing 100:1, you have a serious flow problem. If you're seeing 1:1, either you're already very lean or you're miscounting your wait time (very common - people forget the overnight queues, the batch waits, the "waiting for approval" delays).
Measuring wait time honestly
Cycle time is easy - stopwatch the operator. Wait time is harder because it's invisible. Best method: pick 10 real work items and follow them start to finish, recording every timestamp. Compare total elapsed time to sum of cycle times. The difference is your real wait time.