WORKDAY and NETWORKDAYS Functions
How to use Excel's WORKDAY function to calculate project completion dates and NETWORKDAYS to count working days between two dates.
Both WORKDAY and NETWORKDAYS are essential for project planning. WORKDAY calculates a completion date given a start date and number of working days. NETWORKDAYS does the opposite — it calculates how many working days fall between a start date and a target end date. Both functions exclude weekends and can optionally exclude holidays.
WORKDAY Function
WORKDAY(start_date, days, [holidays])
The holidays parameter is optional. If omitted, only weekends are excluded. For more practical results, include a range of holiday dates such as A1:A10. The holiday range can span beyond the project duration — Excel will automatically include only the relevant dates.
NETWORKDAYS Function
NETWORKDAYS(start_date, end_date, [holidays])
NETWORKDAYS uses the same logic as WORKDAY but works in reverse — you provide the desired end date and it returns the number of working days available. This helps you assess whether you have enough resource capacity to meet the deadline, or whether additional resources are needed.