Capacity Requirements in Projects 
Definition
Internal resources required to carry out a project at a particular time
Use
You generate capacity requirements in projects by
Scheduling determines the earliest and latest start and finish dates for performing activities in the network and calculates the required capacity requirements as well as the slack time or "floats" (see
Network Scheduling)The system calculates the capacity requirements for networks using the
formula that you have entered in the capacity detail screen of the work center. Generally, the system uses the value you entered for work in the network activity in the formula; however, you can specify other formula parameters. You must schedule the network in order to have the system calculate the capacity requirements.
To carry out scheduling and to determine capacity requirements the system requires the following data from the work center:

If you do not enter a formula for the capacity requirements, the system does not calculate capacity requirements.
You can create work elements for activities, for instance, if you require several resources to carry out an activity. You enter the same data in work elements as in activities. You specify the date for the work element requirements as an offset to the start or finish date of the activity.
Reduction of Capacity Requirements
As well as partial and final confirmation, the status "technically complete" also affects capacity requirements. When this status, like a final confirmation, is set, the system removes all capacity requirements for a network.
In the case of partial confirmations, the system calculates the remaining capacity requirements by subtracting the actual value for work from the capacity requirements. Alternatively you can enter a forecast value for the remaining work, from which the system can re-calculate the capacity requirements using formulas.
Available Capacities
You define available capacities in the work center using
capacity categories. Available capacity is the output that a capacity category can generate per work center.You can link a
work center or a capacity with objects in the personnel system and use
Workforce Planning.For more information on work centers and the data you enter there for capacity planning, see
Work Centers.