Hello,

Enter into A1:B7, for example:
04:00 23:30
01:00 23:30
01:00 23:30
01:00 23:30
01:00 23:30
09:00 23:30
00:00 00:00

Then count_hours(C1,D1,A1:B7) will give you the hours from C1 till D1if
they are included in table A1:B7 (format resulting cell as dd hh:ss,
for example)

The UDF count_hours:

Function count_hours(dt1 As Date, dt2 As Date, _
vwh As Variant) As Date
'Returns time between dt1 and dt2 but counts only
'hours given in table vwh: for example
'04:00 23:30
'01:00 23:30
'01:00 23:30
'01:00 23:30
'01:00 23:30
'09:00 23:30
'00:00 00:00
'This table defines hours to count for each day
'of the week (starting with Monday, 2 columns)
'PB V0.90
Dim dt3 As Date, dt4 As Date, dt5 As Date
Dim i As Long

If dt2 <= dt1 Then
count_hours = 0#
Exit Function
End If

If (Int(dt1) = Int(dt2)) Then
dt3 = Int(dt2) + vwh(Weekday(dt2, 2), 2)
If dt3 dt2 Then dt3 = dt2
If vwh(Weekday(dt1, 2), 1) = 0 Then
dt4 = Int(dt1)
Else
dt4 = Int(dt1) + vwh(Weekday(dt1, 2), 1)
If dt4 < dt1 Then dt4 = dt1
End If
count_hours = dt3 - dt4
Exit Function
End If

If CDbl(dt1) - Int(CDbl(dt1)) = vwh(Weekday(dt1, 2), 2) Then
dt3 = 0#
Else
If vwh(Weekday(dt1, 2), 1) = 0 Then
dt3 = Int(dt1)
Else
dt3 = Int(dt1) + vwh(Weekday(dt1, 2), 1)
If dt3 < dt1 Then dt3 = dt1
End If
dt3 = Int(dt1) + vwh(Weekday(dt1, 2), 2) - dt3
End If

If CDbl(dt2) - Int(CDbl(dt2)) <= vwh(Weekday(dt2, 2), 1) Then
dt5 = 0#
Else
dt5 = Int(dt2) + vwh(Weekday(dt2, 2), 2)
If dt5 dt2 Then dt5 = dt2
If vwh(Weekday(dt2, 2), 1) = 0 Then
dt5 = dt5 - Int(dt2)
Else
dt5 = dt5 - Int(dt2) - vwh(Weekday(dt2, 2), 1)
End If
End If

If Int(dt2) - Int(dt1) 1 Then
dt4 = 0#
For i = Int(dt1) + 1 To Int(dt2) - 1
dt4 = dt4 + vwh(Weekday(i, 2), 2) - vwh(Weekday(i, 2), 1)
Next i
End If

count_hours = dt3 + dt4 + dt5

End Function

HTH,
Bernd