I read through Chip Pearson's page, admittedly its a bit above my
skill level implementing that into my code.
http://www.cpearson.com/excel/TimeZoneAndDaylightTime.aspx
I think there's an error in the late Chips code - his ConvertLocalToGMT
and GetLocalTimeFromGMT
uses a variable called StartTime
- I think in both cases this should be the variable that is being passed to the function.
To use his code you'd write something like:
Range("A1") = GetLocalTimeFromGMT(Now())
or
Range("A1") = ConvertLocalToGMT(Now())
I've included the code from his site below. Just copy and paste into a new module.
Option Explicit
Private Type SYSTEMTIME
wYear As Integer
wMonth As Integer
wDayOfWeek As Integer
wDay As Integer
wHour As Integer
wMinute As Integer
wSecond As Integer
wMilliseconds As Integer
End Type
Private Type TIME_ZONE_INFORMATION
Bias As Long
StandardName(0 To 31) As Integer
StandardDate As SYSTEMTIME
StandardBias As Long
DaylightName(0 To 31) As Integer
DaylightDate As SYSTEMTIME
DaylightBias As Long
End Type
Private Enum TIME_ZONE
TIME_ZONE_ID_INVALID = 0 ' Cannot determine DST
TIME_ZONE_STANDARD = 1 ' Standard Time, not Daylight
TIME_ZONE_DAYLIGHT = 2 ' Daylight Time, not Standard
End Enum
Private Declare Function GetTimeZoneInformation Lib "kernel32" _
(lpTimeZoneInformation As TIME_ZONE_INFORMATION) As Long
Private Declare Sub GetSystemTime Lib "kernel32" _
(lpSystemTime As SYSTEMTIME)
Function ConvertLocalToGMT(Optional LocalTime As Date) As Date
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' ConvertLocalToGMT
' This function returns the GMT based on LocalTime, if provided.
' If LocalTime is not equal to 0, the GMT corresponding to LocalTime
' is returned. If LocalTime is 0, the GMT corresponding to the local
' time is returned. Since GMT isn't affected by DST, we need to
' subtract 1 hour if we are presently in GMT.
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Dim T As Date
Dim TZI As TIME_ZONE_INFORMATION
Dim DST As TIME_ZONE
Dim GMT As Date
If LocalTime <= 0 Then
T = Now
Else
T = LocalTime
End If
DST = GetTimeZoneInformation(TZI)
GMT = T + TimeSerial(0, TZI.Bias, 0) - IIf(DST = TIME_ZONE_DAYLIGHT, TimeSerial(1, 0, 0), 0)
ConvertLocalToGMT = GMT
End Function
Function GetLocalTimeFromGMT(Optional GMTTime As Date) As Date
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' GetLocalTimeFromGMT
' This returns the Local Time from a GMT time. If GMTTime is present and
' greater than 0, it is assumed to be the GMT from which we will calculate
' Local Time. If GMTTime is 0 or omitted, it is assumed to be the GMT
' time.
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Dim GMT As Date
Dim TZI As TIME_ZONE_INFORMATION
Dim DST As TIME_ZONE
Dim LocalTime As Date
If GMTTime <= 0 Then
GMT = Now
Else
GMT = GMTTime
End If
DST = GetTimeZoneInformation(TZI)
LocalTime = GMT - TimeSerial(0, TZI.Bias, 0) + IIf(DST = TIME_ZONE_DAYLIGHT, TimeSerial(1, 0, 0), 0)
GetLocalTimeFromGMT = LocalTime
End Function