Remember that we have been discussing effort in this chapter, calculating it in ideal engineering hours. You need to convert this into actual calendar time, taking into account vacation, illness, training, the support of the existing systems, tasks for other projects, company meetings, and many other things.

If you have already implemented detailed time tracking in your organization, you can get a good idea of the development efficiency of each developer from historical data. If you do not have this data, start your project plan assuming 50 percent efficiency for everyone. Then, follow up on how many hours are actually spent on development tasks for each person. This can be very different from person to person because of the varying other tasks each team member will have.