Response time in hours and minutes excluding weekends and holidays

I am struggling to develop a formula to calculate response time for technical support calls at our company. Below are a few examples from my data set and the current formula I am using.

Incoming date/time Response date/time Total [h]:mm:ss
1/02/18 07:54:00 1/05/18 08:32:00 27:38:00
1/02/18 08:36:00 1/02/18 08:39:00 0:03:00
1/02/18 08:58:00 1/02/18 09:05:00 0:07:00
1/02/18 09:08:00 1/03/18 10:22:00 10:14:00
1/02/18 09:12:00 1/02/18 10:19:00 1:07:00
1/02/18 09:22:00 1/02/18 09:31:00 0:09:00


Formula - Current

R = incoming date and time for call
S = response date and time for call
W = work time end
V = work time start

=(NETWORKDAYS(R2,S2)-1)*($W$2-$V$2)+(MOD(S2,1)-MOD(R2,1))

The problem I am running into is calls can come in outside of the normal business hours set in W and V (8am-5pm) and on the weekends. Our support engineers sometimes show up early and respond to calls before 8am or stay late and respond to calls after 5pm. I want to calculate our response time for normal business hours, so if a call comes in on the weekend, the incoming time should be calculated for Monday at 8am start and end no matter what time it is for the response date/time. My current formula errors (with a negative) for the following scenario


Incoming date/time Response date/time
1/13/18 11:49:00 1/15/18 10:51:00
1/23/18 17:00:00 1/24/18 07:52:00
1/27/18 09:43:00 1/29/18 09:15:00
1/31/18 17:36:00 2/01/18 08:15:00
2/01/18 19:11:00 2/02/18 08:39:00
2/02/18 15:35:00 2/03/18 14:00:00
2/04/18 20:54:00 2/05/18 08:29:00
2/04/18 21:09:00 2/05/18 08:30:00
2/05/18 18:56:00 2/06/18 08:14:00
2/28/18 22:53:00 3/01/18 08:26:00
3/03/18 12:28:00 3/05/18 07:55:00
3/06/18 17:30:00 3/07/18 07:57:00
3/06/18 21:58:00 3/07/18 08:13:00
3/07/18 17:33:00 3/08/18 07:59:00
3/13/18 17:42:00 3/14/18 08:02:00
3/13/18 21:54:00 3/14/18 10:07:00
3/23/18 19:16:00 3/26/18 08:48:00
3/26/18 21:56:00 3/27/18 08:30:00
3/28/18 22:10:00 3/29/18 09:08:00
4/04/18 17:43:00 4/05/18 08:00:00
4/04/18 17:49:00 4/05/18 08:06:00
4/04/18 18:43:00 4/05/18 08:48:00
4/10/18 23:44:00 4/11/18 08:54:00
4/11/18 19:57:00 4/12/18 07:44:00
4/11/18 21:02:00 4/12/18 07:44:00
4/11/18 23:25:00 4/12/18 07:46:00
4/13/18 13:33:00 4/16/18 00:00:00
4/16/18 10:37:00 4/16/18 00:00:00
4/20/18 17:23:00 4/23/18 07:42:00
4/20/18 19:46:00 4/23/18 07:55:00
4/21/18 22:39:00 4/24/18 10:17:00
4/25/18 21:58:00 4/26/18 09:55:00
4/28/18 16:57:00 4/30/18 11:33:00
4/30/18 23:18:00 5/01/18 10:32:00
5/03/18 17:09:00 5/04/18 08:03:00
5/10/18 16:57:00 5/11/18 07:38:00
5/12/18 14:41:00 5/14/18 07:56:00
5/31/18 20:04:00 6/01/18 08:20:00
5/31/18 21:18:00 6/01/18 08:31:00
6/04/18 12:01:00 6/04/18 12:00:00
6/07/18 17:49:00 6/08/18 08:10:00
6/11/18 18:14:00 6/12/18 08:26:00
6/12/18 23:51:00 6/13/18 08:03:00
6/24/18 21:35:00 6/25/18 07:53:00
6/24/18 22:00:00 6/25/18 08:08:00
6/24/18 22:14:00 6/25/18 08:09:00

Any advice would be much appreciated on this!

EDIT: I have added the Excel workbook I am working on with examples of correct and incorrect values.

Welcome to the forum! Here's the first bit of advice:

Will you please attach a sample Excel workbook? We are not able to work with or manipulate a picture of one and nobody wants to have to recreate your data from scratch.

1. Make sure that your sample data are REPRESENTATIVE of your real data. The use of unrepresentative data is very frustrating and can lead to long delays in reaching a solution.

2. Make sure that your desired results are also shown (mock up the results manually).

3. Make sure that all confidential data is removed or replaced with dummy data first (e.g. names, addresses, E-mails, etc.).

4. Try to avoid using merged cells as they cause lots of problems.

Unfortunately the attachment icon doesn't work at the moment, so to attach an Excel file you have to do the following: just before posting, scroll down to Go Advanced and then scroll down to Manage Attachments. Now follow the instructions at the top of that screen.

Please pay particular attention to point 2 (above): without an idea of your intended outcomes, it is often very difficult to offer appropriate advice.

See if one of these helps - I think you want the second one NetWorkHours.

Function WorkHours(StartDate As Date, NumHours As Double, ShiftStart As Date, ShiftEnd As Date, _
    Optional Holidays As Range) As Date
Application.Volatile
Dim StartDay As Date            ' Start of the workday
Dim EndDay As Date              ' End of the workday
Dim EndHours As Date            ' Ending time of project
Dim EndDate As Date             ' Ending date of project
Dim DayHours As Double          ' Number of hours in the workday
Dim BeginTime As Date           ' Beginning of task or shift

' Initialize variables
EndDate = StartDate + NumHours / 24
EndDay = Int(StartDate) + ShiftEnd
BeginTime = StartDate - Int(StartDate)

' While the end date still exceeds the end of day for a workday
While EndDate > EndDay
    ' increment EndDay
    EndDay = EndDay + 1
    ' Process only for workdays
    If IsWorkday(EndDay, Range("Holidays")) = True Then
        'decrement the hours
        NumHours = NumHours - 24 * (ShiftEnd - BeginTime)
        BeginTime = ShiftStart  ' Begin time becomes shift start after the first day
        ' Compute new enddate
        EndDate = Int(EndDay) + ShiftStart + NumHours / 24
    Else
        ' increment the end date for weekends and holidays without processing
        EndDate = EndDate + 1
    End If
Wend

WorkHours = EndDate
End Function

Function IsWorkday(MyDate As Date, Optional Holidays As Range) As Boolean
Dim cl As Range             ' Pointer to holiday range
Dim bRtn As Boolean         ' Return value (default = True unless proven otherwise)
Dim WkDay As Long

bRtn = True

' Check to see if the date is on the holiday list
If Not Holidays Is Nothing Then
    For Each cl In Holidays
        If Int(MyDate) = cl.Value Then
            bRtn = False
            Exit For
     End If
    Next
End If

' Check to see if the day is a weekend
WkDay = Weekday(MyDate, vbMonday)

If WkDay > 5 Then
    bRtn = False
End If

IsWorkday = bRtn
       
End Function

OR

Function NetWorkHours(Shift_Start As Date, Shift_End As Date, Start_Time As Date, End_Time As Date, _
    Optional Holidays As Range) As Double
Dim NumHrs As Double
Dim ShiftHrs As Double
Dim DayDiff As Long
Dim DayLoop As Long
Dim DayHoliday As Boolean

ShiftHrs = Shift_End - Shift_Start
NumHrs = 0

' Figure out the number of hours
If Time_Fraction(Start_Time) <= Time_Fraction(End_Time) Then
    NumHrs = Time_Fraction(End_Time) - Time_Fraction(Start_Time)
Else
    NumHrs = (Time_Fraction(Shift_End) - Time_Fraction(Start_Time)) + _
    (Time_Fraction(End_Time) - Time_Fraction(Shift_Start))
End If

' Determine the number of extra days to add
DayDiff = Int(End_Time - Start_Time)
For DayLoop = 1 To DayDiff
    ' check to see if day is a weekend or holiday
    If Holidays Is Nothing Then
        DayHoliday = False
    Else
        DayHoliday = Is_Holiday(Int(Start_Time) + DayLoop)
    End If
    If Weekday(Int(Start_Time) + DayLoop, 2) < 6 And DayHoliday = False Then
        NumHrs = NumHrs + ShiftHrs
    End If
Next DayLoop

NetWorkHours = 24 * NumHrs

End Function

Here is a sample. Note, I don't take into consideration lunch breaks. Also revised code

Function NetWorkHours(Shift_Start As Date, Shift_End As Date, Start_Time As Date, End_Time As Date, _
    Optional Holidays As Range) As Double
Dim NumHrs As Double
Dim ShiftHrs As Double
Dim DayDiff As Long
Dim DayLoop As Long
Dim DayHoliday As Boolean

ShiftHrs = Shift_End - Shift_Start
NumHrs = 0

' Figure out the number of hours
If Time_Fraction(Start_Time) <= Time_Fraction(End_Time) Then
    NumHrs = Time_Fraction(End_Time) - Time_Fraction(Start_Time)
Else
    NumHrs = (Time_Fraction(Shift_End) - Time_Fraction(Start_Time)) + _
    (Time_Fraction(End_Time) - Time_Fraction(Shift_Start))
End If

' Determine the number of extra days to add
DayDiff = Int(End_Time - Start_Time)
For DayLoop = 1 To DayDiff
    ' check to see if day is a weekend or holiday
    If Holidays Is Nothing Then
        DayHoliday = False
    Else
        DayHoliday = Is_Holiday(Int(Start_Time) + DayLoop, Holidays)
    End If
    If Weekday(Int(Start_Time) + DayLoop, 2) < 6 And DayHoliday = False Then
        NumHrs = NumHrs + ShiftHrs
    End If
Next DayLoop

NetWorkHours = 24 * NumHrs

End Function

Function Is_Holiday(MyDate As Date, Holidays As Range) As Boolean
Dim cl As Range                         ' Pointer to Holiday list

' Set to true if date is on the list of holidays
For Each cl In Holidays
    If MyDate = cl.Value Then
        Is_Holiday = True
        Exit Function
    End If
Next cl

Is_Holiday = False
End Function

Function Time_Fraction(MyTime As Date) As Double
Time_Fraction = TimeSerial(Hour(MyTime), Minute(MyTime), Second(MyTime))
End Function

These are user-defined functions and will work either in code or a formulas on the worksheet.

To use NetWorkHours, you must feed it the following parameters:

• Shift Start and Shift End (E.g 08:00, 17:00)
• Task Start and Task End (including date) - E.g. 7/18/2018 12:45, 7/19/2018 09:30
• Range of Holiday Dates (Optional)

In the example above it will compute the time between 12:45 to 17:00 and then add on the time between 8:00 and 9:30.

Posts crossed - see the example.