There are two types of duration in Project. The Duration field’s values are expressed in working time, so a day is 8 hours by default. This is to accommodate resource assignments and to provide a basis for realistic resource scheduling. The figure below illustrates the idea: One resource working 8 hours per day for 5 days results in 40 hours of effort. (Click on the figure to expand.)
Elapsed durations are durations entered with an “e” prefix. For example 2 elapsed days would be entered as “2ed” or “2edays”. An elapsed day is expressed in consecutive calendar time, so 2 elapsed days represents 48 consecutive hours. In the figure below a resource is assigned to a task 5 elapsed days in duration. Notice the amount of work!
It should be obvious that elapsed duration tasks are not designed for human resource assignments. But for intense, machine driven tasks running on a 24 X 7 basis, it is perfect!
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