What is float time in project management

If you’ve been working in project management for a while, you’ll probably have come across float project management.

While less well known than other project management frameworks like Agile or Kanban, float project management can be a great way to supercharge your projects and give your productivity a big lift.

Float project management slots nicely alongside other styles of project management and works as a way of identifying “float” or “slack” time in your project timelines.

Float or slack is the amount of time a project or task can be delayed without it impacting the overall deadline or other tasks in the project. Calculating them can help you validate your project schedules and make sure you understand whether you’ll be able to deliver projects on time.

If you find you already have a good way of managing the tasks that make up a project but struggle with resource management or resource scheduling, float project management can be a great way to balance your team’s time more purposefully and stop projects missing their deadlines.

To help you work out if float project management is something you can integrate into your workflows, we’ve broken down exactly what float project management is, how to identify types of float, how to use the float time formula, and how to implement float project management into your workflows.

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What is Float Project Management?

Float project management is a type of project management that helps you verify your project schedules and work out how much time individual tasks can slip without impacting the overall timeline or delivery date.

Float project management helps you identify individual tasks and project “slack” — that’s how much time and leeway your task has – and helps you use this to determine whether a project schedule is viable and identify which tasks are on a “critical path”.

A critical path is a type of task that cannot be delayed or moved around and must be done exactly on time to maintain the overall schedule. Any delay or movement of the task would result in other tasks being impacted and the project missing the deadline.

The Benefits of Float Project Management

Float project management is very useful because it helps identify which tasks are able to be impacted by delay or restructuring without affecting your overall project. It also helps you stop critical path tasks from being held back or moved which then stops your project from missing the deadline.

Being able to identify float or slack in your projects is incredibly helpful. Spotting flexibility in your schedules means you can amend resource scheduling without needing extra client or management approval for new deadlines. Understanding which tasks have a little give to them can mean that projects can be tweaked to account for staffing changes, resource challenges, and other unforeseen situations that would otherwise lead to you involving your client or managers.

Combining float project management with project management software like Hubstaff Tasks can allow you to have a better grip on your projects and run things more smoothly. Using Hubstaff Tasks’ Kanban-style boards allows you to easily identify task dependencies and work out float time that can be used to make your projects run on schedule and be more efficient.

How to Calculate Float in Project Management

If all of this sounds useful to you, you’re probably wondering how to calculate float time in your projects. Thankfully, float can be fairly easily calculated using the float time formula.

The float time formula works out float using the earliest and latest start or finish times for individual tasks. The formulas are:

Float = Late Start – Early Start 

Float = Late Finish – Early Finish

For example, let’s take two tasks, Task A and Task B. Task B can’t start until Task A is finished and Task A takes 10 days. However, in your schedule, you’ve allocated 17 days for Task A to be completed. That means that Task A could start 7 days after the scheduled start date without impacting Task B. The float for Task A is then 7.

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How to Use Float Project Management with Kanban or Agile

The benefits of float project management are clear but if you’re an advanced user of Agile or Kanban project management styles, you’re forgiven for wondering how float project management can fit seamlessly into these frameworks.

Thankfully, float project management can easily be combined with other project management processes and your existing project management tools like Hubstaff Tasks or Asana to supercharge your projects.

Because float project management requires few changes to the way you manage projects day to day, it runs alongside other forms of project management.

If you’re a fan of Kanban or Agile style project management, you can use float project management to identify your task dependencies, work out tasks that are on a critical path, and then calculate how much slack time your projects have without changing your day-to-day management.

Float project management doesn’t replace existing project management frameworks, it enhances them.

That’s why it works especially well for small businesses that have limited resources and where deadlines are especially important. Float project management allows small businesses to work out which tasks have more slack time and can be put on the back seat temporarily in favor of tasks that are more important right now. This means key problems get addressed and projects don’t run over their timelines.

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For small businesses or experienced project managers, combining with powerful and flexible project management tools like Hubstaff Tasks makes sure projects run efficiently and maximise the amount of float time they have on offer.

Tools like Hubstaff Tasks are especially suited to a float project management style because they allow for efficient project management. Hubstaff Tasks, in particular, uses automated Kanban-style workflows that combine automation to responsively update your project schedules and timelines based on changes.

Using Hubstaff Tasks alongside a flow project management style allows you to have an overview of your project schedule, calculate your float time, and adjust your tasks and project automatically.

Start calculating your tasks’ float time today and combine this efficient project management framework with Hubstaff Tasks to supercharge your team’s productivity and efficiency.

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1. Calculate critical path, project float, early start dates, and late start dates.

The critical path is the path through the network that results in the latest completion date of the project.

Image by Be the Change, Inc.

If any activity on the critical path is delayed, the completion of the project will be delayed by an equal amount. To determine the critical path, add the amount of time estimated for the duration of each activity to the previous activity, as shown in Figure 8.10. Durations are indicated in days and activities on the critical path are shaded. The critical path through these tasks takes at least eight days.

Figure 8.10 Critical Path

Early Start Dates

Starting dates can be assigned to each activity by doing a forward pass proceeding from left to right in the network diagram beginning with the project start date. The dates derived by this method are the early start (ES) dates. The early start date for an activity is the earliest date the activity can begin. The estimate considers durations and resource availability calendars. To calculate early start dates, begin with the project start date and assign that date as the start date of activities that have no predecessor activities. Follow these steps to calculate the early start dates of subsequent activities, assuming finish-start relationships:

• Add the predecessor activity’s duration to its start date.
• Add the lag time or subtract the lead time.
• Refer to the resource calendar(s) that applies to the people and equipment necessary for the activity, and add the number of off-days that the activity would span on those calendars.
• Assign the calculated date as the early start date of the successor activity.

John begins planning his move to Atlanta the same day he accepts the job. The start date in this example is Monday, November 29, 2010. Tasks 1.1 and 2.1 can both start on that day, so the early start dates for tasks 1.1 and 2.1 are November 29. John calculates the early start date for the activities. A partial list is provided below. Compare the figure below and the figure in the next sidebar. Observe that John is willing to work on weekends, but activity 2.2.3 is delayed by two days because one of the moving companies did not provide bids on the weekend. Observe that activity 2.3 has a lead time of one day, but that relationship is between activity 2.1 and 2.3. The network path from activity 1.3 is longer, so the lead time with activity 2.1 is not considered in calculating the early start date of 2.3.

Figure 8.11 Early Start Dates Determined by a Forward Pass

Doing this process manually is error prone and time consuming. Fortunately, there are computer programs to assist in the process, but the project manager must understand the process well enough to recognize computer errors. Computer software must be combined with common sense or good judgment.

Float

Float, sometimes called slack, is the amount of time an activity, network path, or project can be delayed from the early start without changing the completion date of the project.

Total float is the difference between the finish date of the last activity on the critical path and the project completion date. Any delay in an activity on the critical path would reduce the amount of total float available on the project. A project can also have negative float, which means the calculated completion date of the last activity is later than the targeted completion date established at the beginning of the project.

If activities that are not on the critical path have a difference between their early start date and their late start date, those activities can be delayed without affecting the project completion date. The float on those activities is called free float.

The last activity in John’s move has an early start date of December 28 and a duration of one day. John could start work on Wednesday, December 29. John’s first day at work is Monday, January 3, so the project has a total float of five days.

Figure 8.12 Total Project Float

Late Start Dates

The next step is to work through the network diagram from right to left beginning with the mandated completion date, which is a milestone that is set in the project plan. Subtract the duration of each activity in each path to determine the latest date the activity could begin and still meet the project completion date. Resource calendars must be considered in the backward pass as well as the forward pass.

To calculate late start dates, begin with the project completion milestone and assign that date as the finish date of its predecessor activities. Follow these steps to calculate the late start dates of predecessor activities, assuming finish-start relationships:

• Subtract the predecessor activity’s duration from its late finish date.
• Subtract the lag time or add the lead time to the late finish date.
• Refer to the resource calendar(s) that applies to the people and equipment necessary for the activity, and subtract the number of off days that the activity would span on those calendars.
• Assign the calculated date as the late start date of the predecessor activity.

The difference between the early start date and the late start date for activities on the critical path is usually the same as the total float, unless the activities are affected by the resource calendars differently in the forward and backward pass. For example, if a piece of key equipment is only available for a few days, activities that depend on it have the same start and finish dates in the forward and backward passes.

• To calculate total project float, begin at the start date and add the duration of each activity in each possible path through the network diagram, including nonworking days from the resource calendars, to determine the early project end date. The longest path through the network is the critical path. The difference between the early end date and the required completion date of the project is the total project float, and the start date of each activity is the early start date. To calculate the late start dates, begin with the required project completion date and work backward, subtracting the duration of each activity though each possible pathway.