The formula to calculate the number of workdays for any period where the start of the period is in cell `A2` and the end is in cell `B2` with
```
=NETWORKDAYS(A2,B2)
```
To get the number of workdays in a month input the first day of the month in cell `A2` and use `EOMONTH(A2,0)` to get the last day of the month.
```
=NETWORKDAYS(A2, EOMONTH(A2,0))
```
To calculate the number of workable hours in a month multiply by 8.
```
=NETWORKDAYS(A2, EOMONTH(A2,0)) * 8
```