Microsoft Project calculates duration based on working hours and days. The default setting for Microsoft Project is an 8-hour workday, a 40-hour workweek. If your working hours are set from 8 am to 5 pm, that's a 9-hour workday, which might be causing the discrepancy in the duration calculation.
Here's how you can check and adjust your working hours:
- Click on the "File" tab in the top left corner.
- Select "Options" from the drop-down menu.
- In the "Project Options" dialog box, click on the "Schedule" tab.
- Under "Calendar options for this project", you'll find "Hours per day", "Hours per week", and "Days per month". Make sure these are set according to your working hours and days. For a 9-hour workday, you should set "Hours per day" to 9.
- Click "OK" to save your changes.
Remember, the "Duration" field in Microsoft Project is in working days, not calendar days. So, if you have a task that starts on July 8 and ends on July 15, and you're working 9 hours per day, 7 days a week, the duration would be 8 days. But if you're only working 5 days a week (Monday to Friday), the duration would be longer because the weekend days are not counted as working days.