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Microsoft KB Archive/103483

From BetaArchive Wiki

Project Yearly Resource Rates Not Based on 365 Day Calendar.

PSS ID Number: Q103483 Article last modified on 03-15-1995

1.00 3.00 3.00a 4.00 | 1.10 3.00

WINDOWS | MACINTOSH

The information in this article applies to:
- Microsoft Project for Windows, versions 1.0, 3.0, 3.0a, 4.0 - Microsoft Project for the Macintosh, versions 1.1, 3.0

SUMMARY

Microsoft Project uses 52 weeks per year instead of 365 days per year to calculate resources whose rates are yearly based. Because of this, you may get a different resource cost than if you calculate the value by hand based on a daily rate. Consider the following steps that show this behavior.

MORE INFORMATION

Steps to Reproduce Behavior

  1. From the File menu, select New.
  2. Set up Project for a 24 hour calendar. From the Options menu, select Preferences.
  3. Select Default Hours/Day and set to 24.00.
  4. Select Default Hours/Week and set to 168.00.
  5. From the Options menu, select Base Calendar. Choose New.
  6. Name the calendar “24 Hours” without quotation marks.
  7. Select Sunday through Saturday day title
  8. Select the Working options button.
  9. In the hours boxes, type the following times. From: To: 12:00 AM 12:00 AM
  10. Choose the OK button.
  11. Choose the Close button.
  12. Choose Option, Project Info…
  13. In the Calendar box, select the “24 Hours” calendar.
  14. Enter a task, “task 1”, in the task edit sheet in the Name field without the quotation marks and assign a duration of 365 days.
  15. Select task 1.
  16. Click on the Resource Assignment button on the tool bar.
  17. In the Resource box, type “Bob” without the quotation marks.
  18. Choose the Add button.
  19. Choose the Yes button. The Resource Edit Form dialog box appears.
  20. Enter a Std Rate of “$365.00/y” without the quotation marks.
  21. Choose the OK button.
  22. From the Table menu, choose “Cost”.

Microsoft Project shows a cost of $366.00 which is $1.00 more than it should be (you would expect $365.00). Using the above example, Microsoft Project breaks down costs in the following manner:

  • 1 year = 52 weeks * 168 hours (1 week) = 8736 hours (or, 52w * 7d/w = 364d)
  • Hourly rate = $365 / 8736 hours = $0.0417811/hour

However, a cost calculated on days-per-year

  • 365d task = 365d * 24h/d = 8760h,

which turns out to be 1 day longer than the year that Microsoft Project calculates based on 52 weeks.

To see the affect of the rate being based on 52 weeks per year instead of 365 days per year and how numeric rounding affects the cost value:

Duration Cost Calculation
1d $1.00 24h * 0.1417811/h
2d $2.01 48h * 0.1417811/h
10d $10.03 240h * 0.1417811/h
100d $100.27 2400h * 0.1417811/h
200d $200.55 4800h * 0.1417811/h
300d $300.82 7200h * 0.1417811/h
365d $366.00 8760h * 0.1417811/h

The cost for the task 1 is $366.00 whereas the cost would be $365.00 if Microsoft Project calculated the rate based on 365 days per year.

KBCategory: kbusage KBSubcategory:

Additional reference words: 4.0 1.00 1.10 3.00 3.00a

Copyright Microsoft Corporation 1995.