Slack time can be defined as the amount of time an task can be delayed without causing another task to be delayed or impacting the completion date of your project.
There are two things that are needed to calculate the slack time:
- ES – the earliest time when an activity can be started
- LS – the latest time when an activity must be started.
The slack time is calculated as:
Slack Time = LS-ES
ES of T3 is after completion of T1 and T2 so
T5: ES =10+15+18=43
T3: LS =43-18=25
Slack time = ES-LS =25-25=0 // For T3