Lead Time vs. Cycle Time

Lead Time and Cycle Time are two important metrics in Lean and process improvement in general. However, many people do not seem to understand the difference and their relationship. In fact, many use them interchangeably. This can lead to confusion in understanding the true problems in a process, and worse, poor decisions in process improvement.

I often observe such confusion on internet discussions as well as in organizations I support in Lean Six Sigma training and deployment. Here is an example:

Another example on the iSixSigma forum:

Before I refer to a good source to help understand the definitions and application of these terms, let’s consider a simple process doing laundry.

There are 3 steps: wash, dry, fold. If we assume the time to do each load is 30, 45 and 30 minutes, respectively, what are the Lead Time and Cycle Time of the process?

I encourage you to answer this question before going to the following link, which used this simple process to illustrate these terms exactly 10 years ago (04/18/2000).

You may notice that this link is not on Lean or Six Sigma but general business (operations) management. These terms and concepts are not developed by, or limited to, Lean or Six Sigma.

In summary, here are what I use to help understand the difference and their relationship.

1. Lead Time and Cycle Time don’t have the same unit although their names are both “Time.” Lead Time is measured by elapsed time (minutes, hours, etc.), whereas Cycle Time is measured by the amount of time per unit (minutes/customer, hours/part, etc.). It does not make any sense to add one to, or subtract one from, another.

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2. Cycle Time is actually a measure of Throughput (units per period of time), which is the reciprocal of Cycle Time. This relationship is analogous to Takt Time (amount of time per unit), which is the reciprocal of customer demand rate (units per period of time). Note that by definition, Cycle Time (or Takt Time) is an average value.

3. Lead Time and Cycle Time are related by Work-in-progress (WIP) in the entire process, in a relationship described by the Little’s Law:

Lead Time = Cycle Time * WIP


Lead Time = WIP/Throughput

4. The Cycle Time above must be the process cycle time, which is determined by the bottleneck. Cycle Times of individual steps cannot be used alone to calculate the process Lead Time without knowing the WIP.

Comments 24

  1. Sue Kozlowski

    Thanks for clearing up a general misconception. I myself used the term incorrectly for a while, then realized the difference – as you put it so clearly – and now I make sure to stress the distinction so others will not have the same confusion I did. In manufacturing, it may be self-evident, but in a service industry without automated / regulated flow, the terms are similar enough that it’s easy to be confused if you don’t start with a good definition. Thanks for giving us that and a good example as well,
    Sue K.

  2. icra ihaleleri

    thanks for sharing. To help me

  3. Compare ISAs

    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

  4. Fang Zhou

    The above Cycle Time defintion is common but can be confusing as a measure of process capability (capability=probability of meeting specific customer requirements). It’s really an internal lead time, a part of the customer lead time. I would simply call it "internal production lead time" to distinguish it from the real customer delivery lead time.

    In addition, work pieces are rarely tracked individually because parts are often produced in advance and stored in the buffers at various process stages ready to be pulled based on customer demand (or Kanban). What is the cycle time of your process (as a capability measure) if some or all work is already done before the request?

    One still needs the REAL cycle time (a throughput or capacity measure). Without it, it’s hard to determine if the process has sufficent capacity to meet customer demand (takt time). When the throughput is less than the demand, the cycle time as defined above no longer measures the process capability to meet customer Lead time requirements.

    In a Pull system, we need to achieve the desired Lead time by controling the WIP. But we need to know the process throughput or the REAL cycle time (Little’s law: Lead Time = WIP * Cycle Time).

    To measure the process capacity, one needs to know HOW OFTEN the process can start or generate a new piece, which is the definition of the REAL cycle time.

  5. Kevin

    We have a story which analysis has been completed, so we moved it from ’Analysis Pipeline’ to next state ’Development Buffer’.

    Then the Product Owner realized that some definitions were missed, so.. should the story be moved back to ’Analysis Pipeline’?

    We have a property which is ’Analysis Completed On’ (that we use for metrics.. to calculate the time stories spend ’In Analysis’), that would be reset. Is that ok? Or should we not move the story back to ’Analysis Pipeline’ and complete those pending definitions leaving the story where it is.. in ’Development Buffer’ state?

  6. Lead answer

    If that is the difference between these two than what we called the recycle time and activity time cause they play a significant role in getting the full section of science

  7. lead answer @ leading way

    Hi, thanks for the information here. I came to realize that lead time and lead cycle are two different things but you are co-relating these. Why can’t we say it recycle time cause your definition is sending this message otherwise all things are good and you help me to overcome the misconception about the leading time.

  8. Dung Huynh

    Dear Sir/Madam.
    1 sheet ceramic have diced into 9 pieces Each machine dices 1 sheet per 1 time on 20 min. If i have 1 operator who control 3 machine to dice ceramics at the same time. How can i count cycle time of this step.
    Thanks and regards!

  9. fzhou

    Hi Dung,

    If I understand your question correctly, the calculation is as below.

    output = 9 pieces/machine x 3 machines = 27 pieces
    time = 20 minutes

    cycle time = time/output = 20 minutes/27 pieces = 0.74 minutes/piece


    Thanks for clarification of confusion which i was having…now i will use that correctly in plant process engineering ..

  11. Nandakumar Pachikide

    This is really an eye opener. It clarifies a lot about lead time and cycle time, which otherwise seem to be the same.

  12. MR Marti

    Then, the cycle time per machine to produce 9 units is different from the total cycle time to produce 27 units?

  13. Adinora

    Hi, just want to clarify.. is that
    change over time = lead time
    please advise

  14. Jack Whoopy

    Good, clear explain and easy to understand.

  15. Matthias

    Hi Fang Zhou.

    Actually I think this is not fully correct. It seems it depends on the context:

    Poppendieck, M., & Poppendieck, T. (2003).Lean Software Development: An AgileToolkit. Addison-Wesley.
    Page 77

    “The use of the term cycle time to denote the average duration of a process is common in product development and supply chain management. When the term cycle time is used in reference to load balancing a manufacturing line, it has a different meaning; it refers to the average rate at which the line produces product.”

  16. Lee Mewshaw

    You have an error here in your wording: “Cycle Time is actually a measure of Throughput (units per period of time), which is the reciprocal of Cycle Time.” Something can’t be the reciprocal of itself.

  17. Amit

    Dear Mrs. Fang,
    Where can i found the example of calculation the one with the laydry machine?

  18. habib ur rehman

    i have a question i am confusing process time and standard time what is the difference between std time or process time

  19. ali abidi

    Amazing. Thanks for sharing.

  20. Charles

    This is good. It’s interesting that in Lean Enterprise they choose to do away with the term “cycle time” altogether, noting that everyone seems to mean something different by it. Instead they use the term “process time,” which is the amount of time actually spent working on the item. Process time divided by lead time then can be a measure of “wait waste,” as discussed in The DevOps Handbook.

  21. David Timmerman

    I would disagree on one major account: Cycle time is NOT takt time, in fact the two are absolutely not related. Too many people get that wrong.

    Cycle time is the time it take to complete your task or piece of the process (washing, loading or drying).
    Takt time is the pace at which you need to produce to meet customer demand. It is available working time divided by customer demand in that period of time. Say if you have 5 working hours available to do laundry and you have 10 customers a day that need your services, your takt time is 5/10=0.5. So you need to deliver a clean load every .5 hrs, or every 30 minutes. It is solely a calculated time based on your available working time and customer demand. It has nothing to do with your cycle time which is how long it takes you to perform a task.
    The time to wash might be 60 minutes or might be, 90 minutes. In which case you can use your cycle time to calculate how many machines you should have or people washing (if hand washing).
    In this case you would CALCULATE the number of resources you need:
    (cycle time) / (Takt time) = # of resources needed. In this case 60 / 30 = 2. So you would need 2 machines to meet your takt time.

  22. David Timmerman

    Note: In a true lean operations you eventually get to duration of Cycle Time = Takt time…

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