Confusion on Lead and Lag


I am getting confused between Lead and Lag.

 My question is simple

 when calculating via a diagram, should we Add or Subtract Duration for a Lead / Lag ?


Example: SF + 45 d, SF -45d


I know Lag is waiting time, and Lead is starting an activity before the predecessor finishes.



admin's picture

The trick is to remember this with some example in mind , Like

Lead time :  3 weeks before the resource can become productive on project.

Lag time:    3 days for curing the cement.

Hence for an activity you will have to add the lag time to get the full duration of the activity.

If there is a lead time of 3 weeks to get some person on the project that means your activity will have to take into account that time and add that to total activity duration.

Depends on the question really.