Free Slack and Total Slack
While dealing with some projects, it is a must to have proper project management. Project scheduling is one of the important aspects of project management, in which, one has to list all the milestones, activities, etc for some projects, with the start date and the end date, with a sequence that can lead to effective execution.
We are not going to go into the details of aspects of project management, but in this article, we are going to understand the difference between free slack, and total slack.
Free Slack Vs Total Slack
As it is mentioned earlier, In project management, project scheduling is one of the very important tasks. Slack (also called float) is the amount of time some task can slip before it bumps into another task. You can use it as a buffer time whenever needed if your task is at risk of delay. In other words, we can say that slack is the time by which, you can delay a task, without interfering with another task.
There are two types of slack – Free slack, and Total Slack. Here, we are going to understand what we mean by Free slack, and what we mean by Total slack, and also we would understand what is the difference between free slack and total slack.
Comparison between free slack and total slack can show how these terminologies differentiate from each other, and what they mean. It becomes important to understand when you are part of some project or someone who needs to handle the project.
1. Difference Between Free Slack and Total Slack
What is Free Slack:
Free slack for some activities can be simply defined as the time, by which we can delay the activity, without causing any impact on the following activity.
In other words, we can define total slack as – “It is the amount of time in which we can delay the scheduled activity, without delaying the following activity”
What is Total slack?
The total slack of an activity can be simply defined as the time, by which the activity can be delayed, without having an impact on the finish date of the project.
In other words, we can define Total Slack as – “It is the amount of time in which schedule activity can be delayed or expanded from its starting date without delaying the project finish date or violating a scheduled constraint”
2. Total Slack and Free Slack Formula
Now, that we are quite familiar with what we mean by the free slack and total slack, let’s now try to have a look at the formula to calculate the free slack and total slack.
Formula to calculate free slack(free float) –
We can calculate the free slack (or free float) by subtracting the early finish date of the current activity, from the early start of the next activity.
So, here is the formula to calculate the free slack –
Free Slack = ES(Early Start) Of Successor – EF(Early finish) of current activity.
Formula to calculate Total Slack :
The total slack can be calculated by subtracting the early start date of the activity, from its last date. Or we can also get the total slack by subtracting the early finish date of the activity from its late finish date.
Total Slack = LS – ES
Total Slack = LF – EF
Note: Here ‘LS’ indicate a late start date, while ‘ES’ indicate to early start date. Same way ‘LF’ indicate to late finish date, while ‘EF’ indicate to early finish date.
3. In Terms of Flexibility
When we need to discuss flexibility then Free Slack is the activity-based flexibility, whereinto the amount of time you can delay the current project activity, without delaying the successor project’s early start date.
Total Slack gives project-level flexibility, which means here activity may be delayed without delaying the project finish date.
4. Free Slack Other Name
Free Slack is also known as a ‘Free Float’.
In another way, Total Slack is well known as a ‘Total Float’.
A task with zero Free Slack or Float is considered to be a critical task, in that case, if a critical task goes delayed then the project finish date will also be delayed.
Total Slack can be either negative or positive, here if the Total Slack is negative that means the project is behind schedule. While if Total Slack is positive then it shows that amount of time for the activity can be delayed without delaying the project finish date.
In this article, we have seen about Free slack and total slack. We have also seen some points of differences related to Free slack and Total slack. We hope that you have got a clear idea about Free slack and total slack.
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Frequently Asked Quiz Questions About Free Slack Vs Total Slack
Ans: Yes it is true.
Ans: Free Slack.
Ans: Total Slack.
Ans: If Total Slack is negative then it indicates that the project is behind schedule.
Ans: When the total slack is positive, it means that we can delay the task by some time.