How to use DateDiff function in VBA?

The DateDiff function in VBA (Visual Basic for Applications) is used to calculate the difference between two dates. This function can be particularly useful in Excel, Access, or other applications that use VBA for automation.

Basic syntax

DateDiff(interval, date1, date2, [firstdayofweek], [firstweekofyear])

Here’s what each parameter means:

  • interval: A string expression that specifies the time interval to use when calculating the difference between date1 and date2. Common intervals include:
    • “yyyy” (Year)
    • “q” (Quarter)
    • “m” (Month)
    • “y” (Day of year)
    • “d” (Day)
    • “w” (Weekday)
    • “ww” (Week of year)
    • “h” (Hour)
    • “n” (Minute)
    • “s” (Second).
  • date1, date2: These are the two dates you want to compare. date1 is typically the earlier date, and date2 the later date.
  • firstdayofweek (optional): A constant that specifies the first day of the week. If not specified, Sunday is assumed. You can use vbSunday, vbMonday, vbTuesday, etc.
  • firstweekofyear (optional): A constant that specifies the first week of the year. If not specified, the first week is assumed to be the week in which January 1st occurs. You can use vbFirstJan1, vbFirstFourDays, or vbFirstFullWeek.


To calculate the number of days between two dates:

Dim diff As Long
diff = DateDiff("d", "1/1/2020", "12/31/2020")
MsgBox "The difference in days is " & diff

This example will show a message box with the number of days between January 1, 2020, and December 31, 2020.

Remember that the DateDiff function can be very versatile depending on the interval you choose, and it’s widely used in automating and scripting within VBA-enabled applications.

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