Takt time is how often demand needs a finished unit. Cycle time is how often the process actually finishes one. Lead time is how long one unit spends in the process from start to finish. The first is set by the customer, the second by the process, and the third mostly by how much work in process sits in queues. The table below puts the three side by side, and a worked line shows all three measured on the same four stations. For takt on its own, see the takt time guide or the free takt time calculator.
The three at a glance
| Takt time | Cycle time | Lead time | |
|---|---|---|---|
| Question | How often must a unit be finished? | How often does the process finish one? | How long does one unit spend in the process? |
| Formula | Net available time ÷ demand | Net production time ÷ units made, or timed per station | WIP ÷ throughput (Little's Law), or timed start to finish |
| Set by | The customer and the shift pattern | The work content, method and losses | Mostly queues: how much WIP sits between steps |
| Typical unit | Seconds or minutes per unit | Seconds or minutes per unit | Minutes, hours or days |
| On the line below | 60 s | 64 s at the bottleneck | 128 min |
| Free calculator | Takt time | Cycle time | Little's Law |
One line, all three measured
A four-station assembly line has 450 net minutes a shift (27,000 seconds) and must ship 450 units a shift. Timed cycle times are 52, 58, 64 and 49 seconds. A walk of the line counts 120 units of work in process, mostly in queues between stations.
Line cycle time = slowest station = 64 s (station 3)
Output per shift = 27,000 ÷ 64 = 421 units, 29 short of 450
Lead time = WIP ÷ throughput = 120 × 64 s = 7,680 s = 128 min
Processing time = 52 + 58 + 64 + 49 = 223 s, about 3.7 min
Three different numbers, three different problems. The line is too slow for demand (cycle time above takt), and a unit spends 128 minutes in a process that touches it for under 4 (lead time far above processing time).
27,000 s ÷ 450 units = 60 s takt. Station cycle times 52, 58, 64 and 49 s. Output = 27,000 ÷ 64 = 421 units a shift.
Fixing each one
Cycle time above takt. Move 6 seconds of work from station 3 to station 4. Cycle times become 52, 58, 58 and 55 seconds; the slowest is now 58 seconds, under the 60-second takt, and the line can make 27,000 ÷ 58 = 465 units a shift. A yamazumi chart is the usual way to find which elements to move.
Lead time far above processing time. Cut the WIP. If the line holds 40 units instead of 120 and runs to takt (one unit every 60 seconds), lead time = 40 × 60 s = 40 minutes. Nothing about the work changed; the units just wait less. The Little's Law guide explains why this always holds.
Takt. Takt is not fixed by the line. It changes only when demand or available time changes, and it is the number the other two are judged against.
When cycle time is above takt
A station with cycle time above takt falls behind on every cycle. The options, roughly in order of cost:
- Rebalance: move work elements to stations with time to spare.
- Remove waste from the station: walking, searching, waiting for the machine.
- Shorten machine time or changeovers on that station.
- Add a second operator or a parallel station.
- Add time: overtime or another shift, which lengthens takt.
The line balancing guide and the line balancing calculator cover the first option in detail.
When cycle time is far below takt
A line whose stations all run well under takt can make more than demand. If it runs flat out, it builds finished goods nobody ordered and hides problems under inventory. Run it at takt with fewer people, or use the spare time for planned maintenance, training and improvement, and plan staffing from takt with the takt time calculator.
Why lead time is mostly waiting
On the example line a unit spends 223 seconds being worked on and 128 minutes in the process. The rest is queue time. By Little's Law, lead time = WIP ÷ throughput, so at a fixed output rate the only way to shorten lead time is to hold less work in process. A value stream map shows where it sits: see value stream mapping, and run the numbers in the Little's Law calculator.
Watch out: "cycle time" has several meanings
- Station or operator cycle time: the time to complete one unit's work at one station. This is what you compare with takt.
- Machine cycle time: the automatic run time of a machine for one part, without loading and unloading.
- Line cycle time: the time between finished units at the end of the line, set by the slowest station.
- "Manufacturing cycle time" or "order cycle time": some plants, and most software teams, use cycle time to mean the time from start to finish of one item. That is lead time in this guide.
When a number is quoted in a meeting, ask which one it is. The glossary defines takt time, cycle time, lead time and Little's Law.
For designing a line against takt offline, with station balancing and a future state, see Line Designer Pro.
Questions
What is the difference between takt time and cycle time?
Takt time is the pace customer demand requires: net available time divided by demand. Cycle time is the time the process actually takes to finish one unit at a station or at the line. Takt comes from the customer; cycle time comes from the process. Every station needs a cycle time at or just below takt.
What is the difference between cycle time and lead time?
Cycle time is the time between finished units at one station or line, or the time to process one unit there. Lead time is the total time one unit spends in the process from start to finish, including every queue. On most lines lead time is many times the sum of the cycle times, because units spend most of their time waiting.
What happens if cycle time is longer than takt time?
The station with cycle time above takt finishes fewer units than demand needs, every shift. At a 64 second cycle against a 60 second takt, a 450 minute shift makes about 421 units instead of 450. The gap must be closed by rebalancing work, removing waste, adding capacity or overtime.
Which is longer: takt time, cycle time or lead time?
Lead time is almost always the longest, because it includes every step and every queue. The bottleneck cycle time should be at or just below takt. Takt itself is independent of the process: it only changes when demand or available time changes.
How do you calculate lead time from WIP?
Use Little's Law: lead time = work in process / throughput. A line holding 120 units of WIP and finishing one unit every 64 seconds has a lead time of 120 x 64 = 7,680 seconds, or 128 minutes.
Is throughput time the same as lead time?
Usually, yes: both mean the time one unit takes from entering the process to leaving it. Some plants measure lead time from customer order to delivery instead, which adds order processing and shipping. State which start and end points you use.