Returns the number of time intervals between two specified dates.
DateDiff(interval, date1, date2[, firstdayofweek[, firstweekofyear]])
The DateDiff function syntax has these named arguments:
| Part | Description |
| interval | String expression, as described in Settings, that is the interval of time you use to calculate the difference between date1 and date2. |
| date1, date2 | Two dates you want to use in the calculation. |
| firstdayofweek | A constant, as described in Settings, that specifies the first day of the week. If not specified, Sunday is assumed. |
| firstweekofyear | A constant, as described in Settings, that specifies the first week of the year. If not specified, the first week is assumed to be the week in which January 1 occurs. |
The interval argument has these settings:
| interval | Time interval |
| yyyy | Year |
| q | Quarter |
| m | Month |
| y | Day of year |
| d | Day |
| w | Weekday |
| ww | Week |
| h | Hour |
| n | Minute |
| s | Second |
The firstdayofweek argument has these settings:
| Constant | Value | Description |
| vbUseSystem | 0 | Use application setting if one exists; otherwise use NLS API setting. |
| vbSunday | 1 | Sunday (default) |
| vbMonday | 2 | Monday |
| vbTuesday | 3 | Tuesday |
| vbWednesday | 4 | Wednesday |
| vbThursday | 5 | Thursday |
| vbFriday | 6 | Friday |
| vbSaturday | 7 | Saturday |
The firstweekofyear argument has these settings:
| Constant | Value | Description |
| vbUseSystem | 0 | Use application setting if one exists; otherwise use NLS API setting. |
| vbFirstJan1 | 1 | Start with week in which January 1 occurs (default). |
| vbFirstFourDays | 2 | Start with the first week that has at least four days in the new year. |
| vbFirstFullWeek | 3 | Start with first full week of the year. |
You can use the DateDiff function to determine how many specified time intervals exist between two dates. For example, you might use DateDiff to calculate the number of days between two dates, or the number of weeks between today and the end of the year.
If you want to know the number of days between date1 and date2, you can use either Day of Year (“y”) or Day (“d”).
When interval is Weekday (“w”), DateDiff returns the number of weeks between the two dates. If date1 falls on a Monday, DateDiff counts the number of Mondays until date2. It counts date2 but not date1. If interval is Week (“ww”), however, the DateDiff function returns the number of calendar weeks between the two dates. It counts the number of Sundays between date1 and date2. DateDiff counts date2 if it falls on a Sunday; but it doesn’t count date1, even if it does fall on a Sunday.
If date1 refers to a later point in time than date2, the DateDiff function returns a negative number.
The firstdayofweek argument affects calculations that use the “w” and “ww” interval symbols.
If date is a date literal (a date enclosed by number signs (#)), the year, if specified, becomes a permanent part of that date. However, if date is enclosed in double quotation marks (""), and you omit the year, the current year is inserted in your code each time the date expression is evaluated. This makes it possible to write code that can be used in different years.
DateAdd Function, DatePart Function, Day Function, Format Function, Now Function, Weekday Function, Year Function.
This example uses the DateDiff function to display the number of days between a given date and today.
Dim TheDate As Date ' Declare variables.Msg= InputBox("Enter a date")= "Days from today: " & DateDiff("d", Now, TheDate)Msg
The following examples use the DateDiff function to calculate the number of calendar weeks between the first of the year and today, and the number of days since February 1, 1995 respectively.
Debug.Print DateDiff("ww", "1-1", Now()).Print DateDiff("y", #1-Feb-1995#, Now())
The next example shows how to use the DateDiff function in a query expression. Suppose you have an Orders table that contains an OrderDate field and a ShippedDate field. You can create a calculated field in a query to display the time elapsed between an order date and a shipped date for each order. In the Query window, create a new query by adding the Orders table and dragging the OrderID field to the query design grid. In an empty Field cell, enter the following to create a calculated field.
DaysElapsed: DateDiff("y", [OrderDate], [ShippedDate])