Effort vs Duration vs Elapsed Time

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Designed to help those that are preparing to take the PMP or CAPM Certification Exam, each post within this series presents a comparison of common concepts that appear on the PMP and CAPM exams.

Effort vs Duration vs Elapsed Time

During the “Estimate Activity Durations” process, the effort, duration, and elapsed time are determined for the schedule activities.

Effort

Effort is the number of work units required to complete the activity. Effort may also be referred to as staff-hours, days, or weeks. In order to determine the activity duration, the effort required to complete the activity must be determined first.

Duration

Duration is the total time to complete the activities based on the resources available to the project. Duration does not include holidays or non-working days and may be referred to work days or weeks.

Elapsed Time

Elapsed time is the calendar time or span required to complete the activities based on the resources available. Elapsed time does include holidays and non-working days.

Example

Installing the new drip system for the landscaping is estimated to take 80 hours of effort.

If there is one worker committed to 40 hours per week, the duration would be 10 workdays.
(Effort = 80 hours, Duration = 10 workdays, Elapsed time = 2 weeks)

However, if there are two workers each committed to 40 hours per week, the duration would be 5 workdays.
(Effort = 80 hours, Duration = 5 workdays, Elapsed time = 1 week)

Or if there are two workers committed to 10 hours per week each, the duration would be 20 workdays.
(Effort = 80 hours, Duration = 20 workdays, Elapsed time = 4 weeks)

Summary

To determine the project activity durations, the PM must consider the amount of effort required and the project resources that are available and will be used.

Effort is the number of work units.

Duration is the total time required based on the effort and the resources available (minus holidays and non-work days).

Elapsed time is the calendar time (includes all dates, such as holidays and non-work days).

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