Including Weeks in Elapsed Time

Written by Allen Wyatt (last updated October 30, 2023)
This tip applies to Excel 2007, 2010, 2013, 2016, 2019, and Excel in Microsoft 365


Sally needs a formula that will return the number of years, months, weeks, and days that have elapsed since a beginning date. She's been able to find a formula that shows years, months, and days, but the inclusion of weeks is something that has eluded her for some time.

If Sally needed to only find the number of days or weeks or months or years between two dates, the math is rather simple. (Just calculate the number of days and divide by the appropriate average number of days in the week, month, or year.) That is not what she wants, however. She wants to know an answer that shows the number of elapsed years, months, weeks, and days between two dates.

Thus, if the starting date was June 10, 1966, and the ending date was February 5, 2019, then the answer she seeks would be "52 years, 7 months, 3 weeks, and 5 days." If the ending date is changed to February 7, 2019, then the answer would be "52 years, 7 months, 4 weeks, and 0 days." In this answer, each progressively granular date gradation functions only on the remainder of the preceding parts of the answer.

The formula to which Sally refers—which does not include an indicator for weeks—can be found at this page on the ExcelTips site:

That tip shows several different formulas to arrive at a desired result, most relying on the DATEDIF function. (It doesn't make sense to recreate, on this page, the extensive information provided on the other ExcelTips page. You may want to go take a look at it, however.)

If adding weeks into the mix, the basic idea is to simply use the same DATEDIF approach, show the number of weeks, and adjust the number of days to take those weeks into account, in this manner:

=DATEDIF(A1,B1,"y") & " years, " & DATEDIF(A1,B1,"ym")
& " months, " & INT(DATEDIF(A1,B1,"md")/7) & " weeks, "
& MOD(DATEDIF(A1,B1,"md"),7) & " days"

This is essentially a modified version of the first full DATEDIF formula on the other ExcelTips page, referenced above. It doesn't take grammar and punctuation into account (as do the later formulas on the page), but it provides the desired information. It is a relatively simple extension of this base formula to get the grammar and punctuation correct.

This formula relies on A1 containing the starting date and B1 containing the ending date (the ending date could easily be set to today's date).

ExcelTips is your source for cost-effective Microsoft Excel training. This tip (12947) applies to Microsoft Excel 2007, 2010, 2013, 2016, 2019, and Excel in Microsoft 365.

Author Bio

Allen Wyatt

With more than 50 non-fiction books and numerous magazine articles to his credit, Allen Wyatt is an internationally recognized author. He is president of Sharon Parq Associates, a computer and publishing services company. ...


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What is 3 + 0?

2023-11-13 11:23:17


Many thanks J Woolly for the code below. Mine was presumably way too simple to cope with all the variations. I shall study the code and try to learn from it (as usual). My coding is all just hobby stuff so I really do appreciate the effort and kindness others go to to help me. Your name is familiar to me, so I've obviously used your coding sometime previous. Thanks again

2023-11-03 15:46:42

J. Woolley

You might be interested in the TimeDif function in My Excel Toolbox:
=TimeDif(Start, Finish, [Approximate], [Conversational])
Start and Finish must be numeric or text dates and/or times. TimeDif returns the difference between Start and Finish as text, which can optionally be exact, approximate, or conversational.
Here is a modified conversational version of TimeDif returning years, months, weeks, and days only (ignoring hours, minutes, and seconds) in the style of your function:

Function elapsInclWeeks2(Start As Date, Finish As Date) As String
    Dim dS As Date, dF As Date, dDif As Double, e As String
    Dim y As Long, m As Long, d As Long, w As Long
    Dim y1 As Long, m1 As Long, d1 As Long
    Dim y2 As Long, m2 As Long, d2 As Long
    dDif = Finish - Start
    d = Int(dDif): dS = Int(Start): dF = Int(Finish)
    'check if finish time-of-day is less than start time-of-day
    If (Finish - dF) < (Start - dS) Then dF = dF - 1
    d1 = Day(dS)
    d2 = Day(dF)
    m1 = Month(dS)
    m2 = Month(dF)
    y1 = Year(dS)
    y2 = Year(dF)
    If d2 < d1 Then 'finish day is less than start day
        m2 = m2 - 1
        If m2 = 0 Then m2 = 12: y2 = y2 - 1
        'add previous month's days
        d2 = d2 + Day(DateSerial(y2, (m2 + 1), 0))
    End If
    If d > d2 - d1 Then d = d2 - d1
    w = d \ 7
    d = d Mod 7
    If m2 < m1 Then 'finish month is less than start month
        y2 = y2 - 1
        'add previous year's months
        m2 = m2 + 12
    End If
    m = m2 - m1
    y = y2 - y1
    Dim s(True To False) As String: s(True) = "": s(False) = "s"
    If y Then e = y & " year" & s(y = 1)
    If m Then e = e & IIf(y, ", ", "") & m & " month" & s(m = 1)
    If w Then e = e & IIf(y Or m, ", ", "") & w & " week" & s(w = 1)
    If d Then e = e & IIf(y Or m Or w, ", ", "") & d & " day" & s(d = 1)
    If e = "" Then e = "0 days"
    elapsInclWeeks2 = e
End Function

With some of your dates, for example:
20-Jan-2007 to 08-Feb-2024, "17 years, 2 weeks, 5 days"
20-Jan-2007 to 30-Jan-2024, "17 years, 1 week, 3 days"
20-Jan-2007 to 27-Jan-2024, "17 years, 1 week"
01-Jan-2000 to 01-Oct-2000, "9 months"
01-Jan-2000 to 08-Oct-2000, "9 months, 1 week"
01-Jan-2000 to 31-Oct-2000, "9 months, 4 weeks, 2 days"

2023-11-02 05:57:48


Including Weeks in Elapsed Time

In the earlier tip (T011360), Willy Vanhaelen added a VBA function to do the job for the Elapsed Time formula (for Y,M,D). That was helpful but resulting output was sometimes ‘weird’ as it produced negative portions as in:
Date1 = 20/01/2007; Date2 = 08/02/2024; Result =17 years, 1 month, -12 days.
I have tried to modify this AND include weeks in the result. However the output is still offering some ‘silly’ results:

Function elapsInclWeeks(a As Date, b As Date) As String
'Origin: Excel.Tips T011360 (Alan Wyatt)
'orig function: -- comments in above by Willy Vanhaelen--2016-06-10
Dim d As Integer, w As Integer, m As Integer, y As Integer
Dim s As String
Dim Mflag As Boolean: Mflag = False 'used to correct month value
Dim Yflag As Boolean: Yflag = False 'used to correct year value
'correction for negative output
If DatePart("d", b) <= DatePart("d", a) Then Mflag = True
If DatePart("m", b) = DatePart("m", a) Then Yflag = True
'calc years difference
y = DateDiff("yyyy", a, b)
If Yflag Then y = y - 1
'update value of a so that years match
a = DateAdd("yyyy", y, a)
'calc months difference
m = DateDiff("m", a, b)
If Mflag Then m = m - 1
'update value of a so that months match
a = DateAdd("m", m, a)
'calc weeks difference
w = Int(DateDiff("d", a, b) / 7)
'calc days difference
d = DateDiff("d", a, b) Mod 7
End Function

This ‘almost’ works but for the ‘silly’ output as in:
Date1 = 20/01/2007; Date2 = 30/01/2024; Result = 16 years, 12 months, 1 week, 3 days
Where the original formula* correctly gives: 17 years, 0 months, 1 week, 3 days
I have juggled but cannot spot the ‘error’

Also with start/end dates of:
Date1 = 01/01/2000; Date2 = 01/10/2000;
Function gives: 8 months, 4 weeks, 2 days.
Formula* gives: 9 months
Is this due to the way DateDiff() chops up the year depending on days in the month?

*the formula:
=DATEDIF($A$1,$B$1,"y") & " year(s), " & DATEDIF($A$1,$B$1,"ym")& " month(s), " & INT(DATEDIF($A$1,$B$1,"md")/7) & " week(s), "& MOD(DATEDIF($A$1,$B$1,"md"),7) & " day(s}."

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