What is the amount of time that a task can be delayed?

Leads, lags and float are concepts used in schedule development process. The process of schedule development includes: identification of all activities, sequencing all activities based on dependency, estimating duration of each activity and finalizing the schedule. Leads, lags and float are used as part of activity sequencing process. All activities once sequenced will form a schedule network diagram. Let us first look at the definition of all these three attributes.

Float

Float (also known as slack) is the amount of time by which the start of an activity can be delayed without delaying the project completion time. Every task will have following set of start and finish time. 

• Earliest start time (ES) - The earliest time, an activity can start once the previous dependent activities are over.
• Earliest finish time (EF) - This would be ES + activity duration.
• Latest finish time (LF) - The latest time an activity can finish without delaying the project.
• Latest start time (LS) - This would be LF - activity duration.

Float time of an activity can be calculated by taking the difference between Late Start (LS) and Early Start (ES) OR between Late Finish (LF) and Early Finish (EF).

Float = LS-ES  OR 

=LF-EF

A positive float time indicates the flexibility we will have in delaying the specific activity without delaying the project completion time.

Typically, while doing scheduling, the critical path tasks will have zero float and the non-critical path tasks will have a positive float. That means non-critical path tasks can be delayed to certain extent without compromising on the project completion time. Float time information of tasks is very useful to the project team for taking scheduling decisions when there will be resource constraints.

Lag:

Lag is the amount of wait time between two tasks. Or in other words, lag is the amount of time by which a successor activity will be delayed. Lag can be used in all the four logical relationships in scheduling, such as Finish-to-start (FS), start-to-start (SS), finish-to-finish (FS) and start-to-finish (SF).

In below example, Task A and B have a Finish to Start (FS) relationship. Ideally both A and B should get finished on the 12th day. But when we insert a waiting of time of 2 days before B can start, then both A and B will get completed only on the 14th day.

Lead:

Lead is the amount of time a successor task can be accelerated. Lead can applied only on finish-to-start relationship between two activities. We can see the below example. In the below example, task B can start 2 days before the completion of task A. Hence the start of task B, which ideally would have been on 6th day, will not start on 4th day.

Conclusion:

Float, lead and lag are very important concepts and information for the scheduling team. A PMP training course ensures you get a hold of these concepts. These are used to optimally identify the dependencies and the associated constraints. Float information is useful in resource allocation when there are resource constraints. Lead is used for accelerating start of tasks (fast tracking) for reducing project timelines. Lag is used for ensuring that required idle or wait time after a task is appropriately provisioned.

In project management, “float” or “slack” is the amount of time a task can be delayed without affecting the deadlines of subsequent tasks or the project’s final delivery date. The former is called “free float”, and the latter is called “total float”. Besides, there are two popular tools carrying the same names. Read this article till the end to learn more about these apps and their key functionality.

How Do I Find Float?

The simplest way to compute slack is to subtract the time you’ve allotted to complete a task from the time the task actually takes. For example, if you’ve allotted 10 days for a task, but it only takes you 6 hours to complete, your slack is 4 days. Tasks with zero floats can be considered part of the “critical path” because any delay on these tasks means a delay to the project deadline itself.

To compute the total float, you need to add up the free float of all the other tasks in the project. If the number is positive, you have that much room to finish a project in case of delays or problems. If the number is negative, you don’t have enough time for the project, and it will most likely miss the deadline.

How Can I Maximize Float?

In order to maximize float in project management, you need to identify your critical path and calculate the amount of float in each non-critical task path. It will help if you visualize the project using a Gantt Chart or PERT diagram.

Gantt Chart is a bar chart that illustrates the project plan based on its tasks and timelines.

With these tools, you can reshuffle tasks and consolidate all of your non-critical tasks into as few task chains as possible. You can then reassign resources and work schedules to focus on the critical chain and to increase team productivity and efficiency. It may not change the amount of float, but it will get you the most out of those spare hours.

Make sure you revise your float estimates as the project goes on. If one task takes longer than expected, you have the option of using up estimated float from a task further down the calendar. Some project managers add a little bit more float than necessary as a safety measure against unexpected delays.

Of course, there will be circumstances where your project gets delayed, no matter how well you manage your float time. Learn from these delays and account for them the next time you schedule a project.

Slack and Float Apps in Project Management: Are They Useful?

So are these applications useful in project management? For sure! Each tool solves its own tasks. If you need a dedicated solution to help you ease out the project management process, it’s better and easier to choose a multifunctional tool to cover the full cycle of project delivery. Let’s take a look at the most popular examples of such solutions.  

Birdview PSA

Birdview PSA is a full-cycle platform that helps professional service delivery teams plan, manage, and forecast resources, projects, and finances in one place. With the Birdview advanced resource planning features, managers can schedule projects, assign tasks, and manage the team’s workload to maximize resource utilization. As a result, your organization will be able to fulfill your current project needs and take on more work with confidence.  

Key Features: Resource Management (Resource Loading Center), Project Management and Collaboration, Time Management, BI Reporting and Forecasting, Free Client Portal

Pricing: Starts at $18.88 per user per month (depending on user type)

Trial: Free 14-day trial  

Float

The Float project management tool helps teams to better plan their current and future work. The app primarily works as a collaborative platform for real-time project planning and task scheduling. With Float, teams always know their workload and upcoming project needs and can make adjustments to their schedules when needed.  

Key Features: Resource Management and Scheduling, Time Tracking, Capacity Management, Forecasting and Reporting  

Pricing: Starts at $6 per user per month (depending on user type)

Trial: Free 30-day trial  

Slack

Since we are talking about slack here, we couldn’t leave the app of the same name behind. Slack is a team collaboration platform that initially started as a messaging app for businesses. The solution’s key idea is to bring everyone inside and outside your organization together to work as a whole team for the benefit of your projects. Ideally, tools similar to Slack should be integrated with another tool covering broader project and resource management functionality, such as Birdview PSA. That’s why Birdview PSA offers integration with Slack through Zapier.    

Key Features: Team Collaboration, Messaging, Data and File Sharing, Workflow Builder (Task Automation)

Pricing: Starts at $7.25 per user per month (depending on user type)

Trial: Free 30-day trial