Data Type Duration (duration field: A type of field whose content is expressed as a duration of time. Examples include the Work, Duration, and Delay fields. A duration field includes the duration unit, such as hour, day, or week.)
Entry Type Calculated or entered (calculated or entered field: A field in which the value is determined by Project based on information in other fields. Information that you enter in the field yourself overrides calculated values.)
Description The Actual Duration field shows the span of actual working time for a task so far, based on the scheduled duration and current remaining work or percent complete.
How Calculated If you type a value in the % Complete field, Project calculates actual duration as follows:
Actual Duration = Duration * Percent Complete
If you type a value in the Actual Duration field, Project calculates the Remaining Duration as follows:
Remaining Duration = Duration - Actual Duration
If you enter an actual duration greater than the scheduled duration, Project changes scheduled duration to match the new actual duration, sets the remaining duration to zero, and sets the percent complete to 100.
Best Uses Add the Actual Duration field to a task sheet when you want to view, filter, or edit actual duration for tasks. If you edit this field, however, the remaining duration and percent complete fields is recalculated.
Example The scheduled duration for the "Conduct client meetings" task is 3 days. If the task is 33 percent complete, the actual duration is 1 day.
Remarks Because entering a value in the Actual Duration, Remaining Duration, or % Complete field automatically recalculates the other fields, you should enter a value in only one of these fields for a task.
Editing remaining duration affects total scheduled duration rather than actual duration.
When you enter percent complete or total actual work, Project reschedules remaining work around the status date by default. If you prefer, you can leave these tracking fields in the project as originally scheduled, even if completed work is shown in the future or remaining work is shown in the past. You can turn off these settings in the Project Options dialog box.
To set the status date to a date other than today's date, open the Project Information dialog box.