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How to Calculate the Time Difference Between Dates, Holidays & Networkdays

Project managers and human resource specialists often calculate the total labor costs involved with completing certain tasks. Multiplying the daily payroll costs for employees involved with the project by the total number of days between start and end dates far exceeds the actual labor costs because it does not account for unworked days such as holidays and weekends. Learning to calculate the time difference between dates, holidays and net workdays allows you to determine the total number of billable days for a project.

Instructions

- 1
  Open a spread sheet program such as Excel. Click "New Worksheet" to create a new worksheet.
- 2
  Enter the start date of the project in the first row of the first column. Type the end date for the project in the row immediately below that.
- 3
  Type the dates of any holidays that your company observed between the start and end dates of the project in a new column.
- 4
  Define a blank cell with a function that determines the number of weekdays between two given dates. For example, in Excel, type "=NETWORKDAYS(start_date, end_date)" without the quotation marks to determine the number of weekdays between the two given dates.
- 5
  Subtract the array of holidays from the number of workdays in the range to find the net workdays. For example, in Excel, type "=NETWORKDAYS(start_date, end_date) -- Holiday_Start:Holiday_End" without the quotation marks.

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