Work-in-process limits are fixed constraints that limit how much work is actively being worked on by everyone on a team. See how to use WIP limits to increase speed.

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Teams can use WIP limits to increase speed; this helps them optimize for flow.
Teams can use WIP limits to increase speed; this helps them optimize for flow.

Let’s say that your boss says your team needs to deliver faster to keep up with the competition. You don’t quite know how to respond: You’re already working long hours and weekends to deliver work on time. The faster you try to get things out the door, the more errors and quality issues you seem to face. Your team members are frustrated, and the constant chaos has some team members looking to jump ship.

You’d like to find a way to meet the challenge of delivering faster, without sacrificing quality, effective communication, or morale. Luckily, there is a way to achieve these goals, but it may seem counterintuitive: The way to speed up is to slow down and focus on optimizing flow.

In Kanban, flow refers to the manner by which work moves through a process, from start to finish. Good flow describes a consistent, steady flow of value to the customer. Bad flow describes delivery that is choppy and inconsistent, where unplanned work and firefighting completely disrupt the order of the system on a regular basis.

So, if teams are charged with delivering faster, they need to optimize for flow, not speed: Teams who optimize for flow create and refine a system that is built for quality, sustainability, and reliability. Teams who optimize for speed adopt unhealthy habits that lead to quality issues, delays, employee burnout, and ultimately, unsatisfied customers.

Enter: WIP Limits

So how do teams optimize for flow? By using WIP limits. WIP (work-in-process) limits are fixed constraints that limit how much work is actively being worked on by everyone in a system. They can apply to a lane, a set of lanes, or an individual person, but they’re usually used to manage capacity in all of the active “Doing” lanes on a team’s Kanban board.

The main idea behind WIP limits can be explained by this simple phrase: Stop starting, start finishing.

WIP limits encourage us to finish work that’s already in process before introducing more work into the system. Because the more work teams try to juggle at once, the harder it is to take work to the finish line.

WIP limits help us optimize flow and increase speed by helping us to eliminate waste from our processes. In Lean thinking, waste is defined as anything that does not add value to the customer. Teams operate in environments that are inherently wasteful, where focus and clarity are luxuries. Waste comes in many forms, including:

  • Context switching
  • Excess meetings
  • Communication breakdowns
  • Rework
  • Duplicate effort
  • Handoff delays
  • Missed deadlines

Without limiting WIP, it’s incredibly difficult to see just how wasteful and inefficient our processes truly are, but all of this waste is what is keeping us from being able to deliver quickly.

How WIP Limits Help Teams Increase Speed

WIP limits are communicated as a number. For example, “This board has a WIP limit of seven,” means that up to seven cards (or work items) can be in process without exceeding the limit.

There is no ideal formula for calculating an ideal WIP limit, although a general rule is that they should be slightly constraining, enough that they force your team to make decisions regarding the priority, time sensitivity, and cost of delay of various projects. If your team never hits its WIP limit, this is probably a sign that your WIP limit is too high. If your WIP limit is too high, you won’t truly experience the benefits of limiting WIP.

Implementing WIP limits can be challenging, but they provide the discipline teams need to optimize flow for speedy value delivery. Here are four reasons your team should use WIP limits to improve not only speed, but quality, communication, collaboration, and morale, too.

WIP Limits Encourage More Effective Capacity Management

Every team has a finite amount of time, energy, and brainpower with which it tries to maximize customer value. This is called capacity, and most teams operate under an unfortunate misunderstanding of how to manage it. A typical approach is to try to maximize the capacity of each member of the team so that each individual gets as close to 100% utilization as possible.

If an interstate is at 100% utilization, we call it a traffic jam: Everyone’s trying to go in the same direction, but they are stuck in gridlock. This is also true for teams: If a team member is at 100% utilization, that means they have no capacity to collaborate with their team members, respond to questions, or help each other deliver work across the finish line.

Utilization of 100% means that everyone is impossibly busy, but nothing is actually getting done.

Everyone’s trying to go in the same direction, but they are stuck in a gridlock.

WIP limits help us more effectively utilize the collective efforts of our team members, so instead of a system where each person is trying to push their tasks to the next step, we create a system in which the team collaborates to move work from start to finish as quickly as possible.

This means that although less work is being done at one time, and although some team members may be underutilized at different points in the process, more value is actually getting into the hands of the customer.

WIP Limits Promote Systems Thinking

WIP limits force teams to work together to prioritize, plan, complete, and deploy work. This is a practice known as systems thinking; instead of having everyone working to achieve their own goals, the team coordinates its efforts to achieve its collective goals. Systems thinking enables teams to make better use of each team member’s time, energy, skills, and experience toward achieving its primary objectives.

WIP limits help to ensure that teams are operating with respect to the system’s overall capacity. This enables teams to maintain a fluid, consistent flow of value. WIP limits motivate team members to work together to complete work and move it off the board, rather than piling on more work, to avoid exceeding the WIP limit.

Instead of asking, “What should I pull next?” systems thinking encourages team members to ask, “What can I help deliver across the finish line?” This keeps teams focused on working together to deliver value as quickly as possible.

WIP Limits Enable Continuous Improvement

When we’re overloaded with work, we don’t have the bandwidth to observe and analyze our process. We do anything that we have to get the work done, without paying much attention to whether our process is the most effective or efficient way to do so.

Implementing WIP limits gives us the clarity to understand how work actually flows through our processes, and determine whether or not they are working. In addition to WIP limits, implementing process policies can help hold teams accountable to following a clear, consistent process.

Process policies can include things like:

  • What card details do we fill out before we prioritize cards?
  • Do we only self-assign to cards or is it okay to assign someone when we need them?
  • How do we define when work is “done?”
  • What criteria need to be met before work can leave our “Plan” lane?
  • What criteria need to be met in order to pull in a card that exceeds our WIP limit?
Process policies help to ensure that everyone is following the board in the same way. Consistent board use becomes critical when teams start analyzing Lean metrics because it allows the team to gather meaningful baseline data from which it can begin to identify opportunities for improvement.

WIP Limits Introduce Slack into the System

Earlier, we learned that introducing WIP limits means that we no longer try to keep team members at 100% utilization. This means that at various times, some team members might even be underutilized (if the team has reached its WIP limit and someone can’t contribute to anything currently in progress). In Kanban, this time is referred to as slack time, and it’s seen as an indicator of a healthy system.

Slack time creates space for improving the way we work, which can help us move faster and more efficiently. Team members can use slack time to brainstorm and implement continuous improvement efforts, consume educational content, or brainstorm ideas to optimize current programs. They can update their Kanban boards, organize important documents, or do anything else that will enable them to work faster and more effective at their jobs.

WIP limits can provide teams with the discipline and structure they need to deliver faster, while also helping to improve focus, sustainability, and quality.