Calculate Years, Months, weeks and Days

Question

In my application, a user enters two dates. A scheduled start date, and a scheduled end date. We have to take those dates, and populate 4 fields, based on the difference.

So, lets say he selects 1st Jan, 2010 as a start, and 2nd of March, 2011 as the end, we need to end up with:

Years: 1 Months: 2 Weeks: 0 Days 1

Meaning the total duration is 1 year, 2 months and 1 day.

Is there a standard way of doing this? Or would I need to write a method that has a lot of pretty tricky logic to work it out? I was hoping I'd be lucky, and there would be a date-diff type .Net class available.

You're not getting the answers you want, so here's the T-SQL version: http://stackoverflow.com/questions/57599/how-to-calculate-age-in-t-sql-with-years-months-and-days/57720#57720 — Gabe, Jun 07 '11 at 03:48
See also: http://stackoverflow.com/questions/3054715/c-calculate-accurate-age/3055445#3055445 — Gabe, Jun 07 '11 at 03:52
possible duplicate of [How to get difference between two dates in Year/Month/Week/Day?](http://stackoverflow.com/questions/1083955/how-to-get-difference-between-two-dates-in-year-month-week-day) — marc_s, Jun 07 '11 at 05:06
This link has the answer: http://stackoverflow.com/questions/1083955/how-to-get-difference-between-two-dates-in-year-month-week-day — Steve Wellens, Jun 07 '11 at 03:48
I am Posted This Topic code http://stackoverflow.com/questions/6260372/calculate-years-months-weeks-and-days/19789907#19789907 — Shaik Raffi, Nov 06 '13 at 08:34

score 11 · Accepted Answer · edited May 31 '18 at 18:27

Heres a complete method, weeks are not included, but could be added relatively simply. It's a somewhat complex question (asked in a multitude of ways on stackoverflow and answered poorly in a multitude of ways), but none the less can be answered. The TimeSpan object gives us part of what we need, but only works up through days. I've written a significant number of tests against this method, if you find a hole, please post a comment.

What this will do is compare 2 dates, getting the years, months, days, hours, and minutes. (e.g. some event happened 1 year, 6 months, 3 days, 4 hours and 7 minutes ago)

Because this question has been asked and attempted to be answered so many times, I'm not sure this will ever even get noticed, but if so it should provide value.

    public static void TimeSpanToDateParts(DateTime d1, DateTime d2, out int years, out int months, out int days, out int hours, out int minutes)
    {
        if (d1 < d2)
        {
            var d3 = d2;
            d2 = d1;
            d1 = d3;
        }

        var span = d1 - d2;

        months = 12 * (d1.Year - d2.Year) + (d1.Month - d2.Month);

        //month may need to be decremented because the above calculates the ceiling of the months, not the floor.
        //to do so we increase d2 by the same number of months and compare.
        //(500ms fudge factor because datetimes are not precise enough to compare exactly)
        if (d1.CompareTo(d2.AddMonths(months).AddMilliseconds(-500)) <= 0)
        {
            --months;
        }

        years = months / 12;
        months -= years * 12;

        if (months == 0 && years == 0)
        {
            days = span.Days;
        }
        else
        {
            var md1 = new DateTime(d1.Year, d1.Month, d1.Day);
            // Fixed to use d2.Day instead of d1.Day
            var md2 = new DateTime(d2.Year, d2.Month, d2.Day);
            var mDays = (int) (md1 - md2).TotalDays;

            if (mDays > span.Days)
            {
                mDays = (int)(md1.AddMonths(-1) - md2).TotalDays;
            }

            days = span.Days - mDays;


        }
        hours = span.Hours;
        minutes = span.Minutes;
    }

this one doesnt calculate the 'Days' correctly. For 139 days it should give 4 months and 19 days, its says 30 days instead which is wrong. It also lacks the Weeks. — Jhollman, Jun 17 '19 at 18:19
@Jhollman some months do have 31 days. The span between 2018-03-01 and 2019-03-31 is one year, zero months, 30 days. It would be wrong to call that one year one month. — Ross Presser, May 19 '20 at 12:59
A good answer! However, if a simplification may be suggested: Years = (int)Span.TotalDays / 365; Of course Months counted is still a problem: https://stackoverflow.com/questions/72836322/non-linear-retrieval-of-dictionary-items-between-specific-index-values — Rusty Nail, Jul 02 '22 at 23:22

score 7 · Answer 2 · answered Jun 07 '11 at 06:25

You can use the DateDiff class of this free library:

// ----------------------------------------------------------------------
public void DateDiffSample()
{
  DateTime date1 = new DateTime( 2009, 11, 8, 7, 13, 59 );
  Console.WriteLine( "Date1: {0}", date1 );
  // > Date1: 08.11.2009 07:13:59
  DateTime date2 = new DateTime( 2011, 3, 20, 19, 55, 28 );
  Console.WriteLine( "Date2: {0}", date2 );
  // > Date2: 20.03.2011 19:55:28

  DateDiff dateDiff = new DateDiff( date1, date2 );

  // differences
  Console.WriteLine( "DateDiff.Years: {0}", dateDiff.Years );
  // > DateDiff.Years: 1
  Console.WriteLine( "DateDiff.Quarters: {0}", dateDiff.Quarters );
  // > DateDiff.Quarters: 5
  Console.WriteLine( "DateDiff.Months: {0}", dateDiff.Months );
  // > DateDiff.Months: 16
  Console.WriteLine( "DateDiff.Weeks: {0}", dateDiff.Weeks );
  // > DateDiff.Weeks: 70
  Console.WriteLine( "DateDiff.Days: {0}", dateDiff.Days );
  // > DateDiff.Days: 497
  Console.WriteLine( "DateDiff.Weekdays: {0}", dateDiff.Weekdays );
  // > DateDiff.Weekdays: 71
  Console.WriteLine( "DateDiff.Hours: {0}", dateDiff.Hours );
  // > DateDiff.Hours: 11940
  Console.WriteLine( "DateDiff.Minutes: {0}", dateDiff.Minutes );
  // > DateDiff.Minutes: 716441
  Console.WriteLine( "DateDiff.Seconds: {0}", dateDiff.Seconds );
  // > DateDiff.Seconds: 42986489

  // elapsed
  Console.WriteLine( "DateDiff.ElapsedYears: {0}", dateDiff.ElapsedYears );
  // > DateDiff.ElapsedYears: 1
  Console.WriteLine( "DateDiff.ElapsedMonths: {0}", dateDiff.ElapsedMonths );
  // > DateDiff.ElapsedMonths: 4
  Console.WriteLine( "DateDiff.ElapsedDays: {0}", dateDiff.ElapsedDays );
  // > DateDiff.ElapsedDays: 12
  Console.WriteLine( "DateDiff.ElapsedHours: {0}", dateDiff.ElapsedHours );
  // > DateDiff.ElapsedHours: 12
  Console.WriteLine( "DateDiff.ElapsedMinutes: {0}", dateDiff.ElapsedMinutes );
  // > DateDiff.ElapsedMinutes: 41
  Console.WriteLine( "DateDiff.ElapsedSeconds: {0}", dateDiff.ElapsedSeconds );
  // > DateDiff.ElapsedSeconds: 29
} // DateDiffSample

Cristiano Santos · Answer 3 · 2016-01-21T16:49:33.613

I also needed this but, in my case, without the weeks part (so only years, months and days). Given that, here's what I made:

DateTime startDate = DateTime.ParseExact (start, "dd/MM/yyyy",CultureInfo.InvariantCulture);
DateTime endDate = DateTime.ParseExact (end, "dd/MM/yyyy",CultureInfo.InvariantCulture);
int days=0;
int months = 0;
int years = 0;
//calculate days
if (endDate.Day >= startDate.Day) {
    days = endDate.Day - startDate.Day;
} else {
    var tempDate = endDate.AddMonths (-1);
    int daysInMonth = DateTime.DaysInMonth (tempDate.Year, tempDate.Month);
    days = daysInMonth - (startDate.Day - endDate.Day);
    months--;
}
//calculate months
if (endDate.Month >= startDate.Month) {
    months+=endDate.Month - startDate.Month;
} else {
    months+= 12 - (startDate.Month - endDate.Month);
    years--;
}
//calculate years
years+=endDate.Year - startDate.Year;
Debug.WriteLine (string.Format("{0} years, {1} months, {2} days",years,months,days));

If you want to show this more dynamically, you can also use this code:

//build the string
var result = "";
if (years!=0){
    result = years == 1 ? years + " year" : years + " years";
}
if (months != 0) {
    if (result != "") {
        result += ", ";
    }
    result += months == 1 ? months + " month" : months + " months";
}
if (days != 0) {
    if (result != "") {
        result += ", ";
    }
    result += days == 1 ? days + " day" : days + " days";
}
Debug.WriteLine (result);

Steve Liu · Answer 4 · 2021-05-05T13:51:08.200

This should do it. The key is to reduce days by 1 if there are odd number of leap days in between the given 2 dates.

    /// <summary>
    /// //Assume DateTime dt1 < DateTime dt2, print out difference between dt1 to dt2 in years, months, weeks and days
    /// </summary>
    /// <param name="dt1"></param>
    /// <param name="dt2"></param>
    static void DateDiff(DateTime dt1, DateTime dt2)
    {
        DateTime zeroTime = new DateTime(1, 1, 1);

        int leapDaysInBetween = CountLeapDays(dt1, dt2);

        TimeSpan span = dt2 - dt1;

        int years = (zeroTime + span).Year - 1;
        int months = (zeroTime + span).Month - 1;
        int days = (zeroTime + span).Day - (leapDaysInBetween % 2 == 1 ? 1 : 0);
        int weeks = days / 7;
        int remainingdays = days % 7;

        Console.WriteLine(String.Format("\nThe difference between date {0} and date {1} is: \n\t {2} year(s), {3} month(s), and {4} day(s).", dt1, dt2, years, months, days));
        Console.WriteLine(String.Format("\nThe difference between date {0} and date {1} is: \n\t {2} year(s), {3} month(s), {4} week(s) and {5} day(s).", dt1, dt2, years, months, weeks, remainingdays));
    }

    private static int CountLeapDays(DateTime dt1, DateTime dt2)
    {
        int leapDaysInBetween = 0;
        int year1 = dt1.Year, year2 = dt2.Year;
        DateTime dateValue;

        for (int i = year1; i <= year2; i++)
        {
            if (DateTime.TryParse("02/29/" + i.ToString(), out dateValue))
            {
                if (dateValue >= dt1 && dateValue <= dt2)
                    leapDaysInBetween++;
            }
        }

        return leapDaysInBetween;
    }

Had run these tests:

static void Main(string[] args)
{
    DateDiff(new DateTime(2010, 1, 1), new DateTime(2012, 2, 9));
    DateDiff(new DateTime(2010, 1, 1), new DateTime(2012, 4, 9));
    DateDiff(new DateTime(2010, 1, 1), new DateTime(2020, 2, 9));
    DateDiff(new DateTime(2010, 1, 1), new DateTime(2020, 4, 9));
    DateDiff(new DateTime(2020, 2, 29), new DateTime(2021, 2, 28));
    DateDiff(new DateTime(2019, 2, 28), new DateTime(2021, 2, 28));
}

These are the printouts:

The difference between date 1/1/2010 12:00:00 AM and date 4/9/2012 12:00:00 AM is: 2 year(s), 3 month(s), and 9 day(s).

The difference between date 1/1/2010 12:00:00 AM and date 4/9/2012 12:00:00 AM is: 2 year(s), 3 month(s), 1 week(s) and 2 day(s).

The difference between date 1/1/2010 12:00:00 AM and date 2/9/2020 12:00:00 AM is: 10 year(s), 1 month(s), and 9 day(s).

The difference between date 1/1/2010 12:00:00 AM and date 2/9/2020 12:00:00 AM is: 10 year(s), 1 month(s), 1 week(s) and 2 day(s).

The difference between date 1/1/2010 12:00:00 AM and date 4/9/2020 12:00:00 AM is: 10 year(s), 3 month(s), and 9 day(s).

The difference between date 1/1/2010 12:00:00 AM and date 4/9/2020 12:00:00 AM is: 10 year(s), 3 month(s), 1 week(s) and 2 day(s).

The difference between date 2/29/2020 12:00:00 AM and date 2/28/2021 12:00:00 AM is: 1 year(s), 0 month(s), and 0 day(s).

The difference between date 2/29/2020 12:00:00 AM and date 2/28/2021 12:00:00 AM is: 1 year(s), 0 month(s), 0 week(s) and 0 day(s).

The difference between date 2/28/2019 12:00:00 AM and date 2/28/2021 12:00:00 AM is: 2 year(s), 0 month(s), and 1 day(s).

The difference between date 2/28/2019 12:00:00 AM and date 2/28/2021 12:00:00 AM is: 2 year(s), 0 month(s), 0 week(s) and 1 day(s).

This is probably the best approximation I've seen so far, but it's also [not entirely consistent](https://stackoverflow.com/a/68200511/385995). **Example 1**: 1/31/19 to 3/1/19 is "30 days". This is not wrong, but also not what you'd expect. When you have a start date in January and end date in March, the difference should be at least one month, don't 'you think? **Example 2**: 12/1/19 to 1/31/20 is "2 months, 3 days". No good way to rationalise this. — Mike Fuchs, Jul 01 '21 at 09:15

score 1 · Answer 5 · answered Nov 05 '13 at 13:17

 public partial class Age1 : System.Web.UI.Page
    {
        private int Years;
        private int Months;
        private int Days;
        DateTime Cday;
        DateTime Bday;


        protected void Page_Load(object sender, EventArgs e)
        {
            txtCurrentDate.Enabled = false;
            txtCurrentDate.Text = DateTime.Now.ToString("g");
            Cday = Convert.ToDateTime(txtCurrentDate.Text);
        }

        protected void Button1_Click(object sender, EventArgs e)
        {
            Bday = Convert.ToDateTime(txtBirthdate.Text);
            AgeCaluclation(Bday, Cday);
            txtBirthdate.Text = "";
            txtCurrentDate.Text = "";
            lblAge.Text = this.Years+"  Years "+this.Months+"  Months " +this.Days+ "Days";
        }

        private Age1 AgeCaluclation(DateTime Bday, DateTime Cday)
        {

            if ((Cday.Year - Bday.Year) > 0 || 
               (((Cday.Year - Bday.Year) == 0) && 
               ((Bday.Month < Cday.Month) ||
               ((Bday.Month == Cday.Month) && 
               (Bday.Day <= Cday.Day)))))
            {

                int DaysInBdayMonth = DateTime.DaysInMonth(Bday.Year, Bday.Month);
                int DaysRemain = Cday.Day + (DaysInBdayMonth - Bday.Day);

                    if(Cday.Month > Bday.Month)
                    {
                        this.Years = Cday.Year - Bday.Year;
                        this.Months = Cday.Month - (Bday.Month + 1) + Math.Abs(DaysRemain / DaysInBdayMonth);
                        this.Days = (DaysRemain % DaysInBdayMonth + DaysInBdayMonth) % DaysInBdayMonth;
                    }
                    else if (Cday.Month == Bday.Month)
                    {
                        if (Cday.Day >= Bday.Day)
                        {
                            this.Years = Cday.Year - Bday.Year;
                            this.Months = 0;
                            this.Days = Cday.Day - Bday.Day;
                        }
                        else
                        {
                            this.Years = (Cday.Year - 1) - Bday.Year;
                            this.Months = 11;
                            this.Days = DateTime.DaysInMonth(Bday.Year, Bday.Month) - (Bday.Day - Cday.Day);

                        }
                    }
                    else
                    {
                        this.Years = (Cday.Year - 1) - Bday.Year;
                        this.Months = Cday.Month + (11 - Bday.Month) + Math.Abs(DaysRemain / DaysInBdayMonth);
                        this.Days = (DaysRemain % DaysInBdayMonth + DaysInBdayMonth) % DaysInBdayMonth;
                    }
            }
            else
            {
                throw new ArgumentException("Birthday date must be earlier than current date");
            }
            return this;
        }

    }

AgeCaluclationUsingC# and Asp.net Amazing

Namith Krishnan · Answer 6 · 2018-01-30T08:32:33.847

I had created this one for returning difference in years,month and days between 2 dates.

public static Dictionary<string, int> TimeSpanToDateParts(DateTime fromDate,DateTime toDate)
        {
            int years;
            int months;
            int days;
            Dictionary<string, int> dateParts = new Dictionary<string, int>();
            if (toDate < fromDate)
            {
               return TimeSpanToDateParts(toDate,fromDate);
            }

            var span = toDate - fromDate;

            months = 12 * (toDate.Year - fromDate.Year) + (toDate.Month - fromDate.Month);

            if (toDate.CompareTo(fromDate.AddMonths(months).AddMilliseconds(-500)) <= 0)
            {
                --months;
            }

            years = months / 12;
            months -= years * 12;

            if (months == 0 && years == 0)
            {
                days = span.Days;
            }
            else
            {
                days = toDate.Day;
                if (fromDate.Day > toDate.Day)
                    days = days + (DateTime.DaysInMonth(toDate.Year, toDate.Month - 1) - fromDate.Day);
                else
                    days = days - fromDate.Day;
            }
            dateParts.Add("Years", years);
            dateParts.Add("Months", months);
            dateParts.Add("Days", days);

            return dateParts;
        }

Thanks for your answer. It would be great if you would also add a short explanation and a few comments to your code. This helps people to understand your answer better. — Andre Hofmeister, Jan 30 '18 at 06:37
The DaysInMonth() part will fail, if the toDate value is in January, because it is subtracting 1 form the Month value. To fix: DateTime prevMonthDate = toDate.AddMonths(-1); days = days + (DateTime.DaysInMonth(prevMonthDate.Year, prevMonthDate.Month) - fromDate.Day); — seagulledge, Jan 04 '21 at 18:23

score 1 · Answer 7 · answered Jun 07 '11 at 03:43

I think TimeSpan is what you are looking for, but it does not do years or months because those vary in length.

The below example is from the above link;

// Define two dates.
DateTime date1 = new DateTime(2010, 1, 1, 8, 0, 15);
DateTime date2 = new DateTime(2010, 8, 18, 13, 30, 30);
// Calculate the interval between the two dates.
TimeSpan interval = date2 - date1;
Console.WriteLine("{0} - {1} = {2}", date2, date1, interval.ToString());
// Display individual properties of the resulting TimeSpan object.
Console.WriteLine("   {0,-35} {1,20}", "Value of Days Component:", interval.Days);
Console.WriteLine("   {0,-35} {1,20}", "Total Number of Days:", interval.TotalDays);
Console.WriteLine("   {0,-35} {1,20}", "Value of Hours Component:", interval.Hours);
Console.WriteLine("   {0,-35} {1,20}", "Total Number of Hours:", interval.TotalHours);
Console.WriteLine("   {0,-35} {1,20}", "Value of Minutes Component:", interval.Minutes);
Console.WriteLine("   {0,-35} {1,20}", "Total Number of Minutes:", interval.TotalMinutes);
Console.WriteLine("   {0,-35} {1,20:N0}", "Value of Seconds Component:", interval.Seconds);
Console.WriteLine("   {0,-35} {1,20:N0}", "Total Number of Seconds:", interval.TotalSeconds);
Console.WriteLine("   {0,-35} {1,20:N0}", "Value of Milliseconds Component:", interval.Milliseconds);
Console.WriteLine("   {0,-35} {1,20:N0}", "Total Number of Milliseconds:", interval.TotalMilliseconds);
Console.WriteLine("   {0,-35} {1,20:N0}", "Ticks:", interval.Ticks);
// the example displays the following output:
//       8/18/2010 1:30:30 PM - 1/1/2010 8:00:15 AM = 229.05:30:15
//          Value of Days Component:                             229
//          Total Number of Days:                   229.229340277778
//          Value of Hours Component:                              5
//          Total Number of Hours:                  5501.50416666667
//          Value of Minutes Component:                           30
//          Total Number of Minutes:                       330090.25
//          Value of Seconds Component:                           15
//          Total Number of Seconds:                      19,805,415
//          Value of Milliseconds Component:                       0
//          Total Number of Milliseconds:             19,805,415,000
//          Ticks:                               198,054,150,000,000

That only seems to handle time values... maximum being Hours. — Craig, Jun 07 '11 at 03:53
Why does this get upvotes? This solution does not answer the question. I don't see years, months, weeks and days. — Alex Aza, Jun 07 '11 at 03:58
I like the answer `I think TimeSpan is what you are looking for, but it doesn't do what you asked for` :) — Alex Aza, Jun 07 '11 at 04:00
As Steve W. pointed out http://stackoverflow.com/questions/1083955/how-to-get-difference-between-two-dates-in-year-month-week-day has an accepted answer. However that answers also doesn't fully answer the question, but shows the complexities involved in this sort of calculation. And it does answer the question "Is there a standard way of doing this? Or would I need to write a method that has a lot of pretty tricky logic to work it out?" — Christoph, Jun 07 '11 at 13:32

score 0 · Answer 8 · answered Jun 07 '11 at 03:44

0

Investigate the C# TimeSpan structure. It doesn't do months or years, but it does do days. That makes things easier.

answered Jun 07 '11 at 03:44

Nik

7,113
13
51
80

score 0 · Answer 9 · answered May 02 '21 at 23:42

The logic isn't overly complicated if you first compute the total months and the total days. Then it's easy to do a bit of integer maths with divide and mod.

DateTime start_date = new DateTime(2010, 1, 1);
DateTime end_date = new DateTime(2011, 3, 2);

int diff_years = end_date.Year - start_date.Year;
int diff_months = end_date.Month - start_date.Month;

int total_months = 12 * diff_years + diff_months;
DateTime near_end_date = start_date.AddMonths(total_months);
int total_days = (int)end_date.Subtract(near_end_date).TotalDays;

int years = total_months / 12;
int months = total_months % 12;
int weeks = total_days / 7;
int days = total_days % 7;

Console.WriteLine($"Years: {years} Months: {months} Weeks: {weeks} Days: {days}");

That gives Years: 1 Months: 2 Weeks: 0 Days: 1 as expected.

score 0 · Answer 10 · answered May 14 '21 at 20:04

Heres a converter I just built. I didn't try all of the solutions above but all the ones I did try were still slightly off in one way or another. This takes into account Years, Leap Years, Months, Weeks, Days etc and then grabs the two most useful values last YM or MW or WD or DH. It's simple but I needed it for my project maybe could be of help to someone down the road. And then of course if this is not good for one reason or another I'm sure you all will let me know.

        DateTime beforeDate = topic.lastActive.ToLocalTime();
        DateTime futureDate = DateTime.Now.ToLocalTime();

        int minutes = 0;
        int hours = 0;
        int days = 0;
        int weeks = 0;
        int months = 0;
        int years = 0;

        Dictionary<int, int> dictMonths = new Dictionary<int, int> { };
        dictMonths.Add(1, 31);
        if (DateTime.IsLeapYear(futureDate.Year))
            dictMonths.Add(2, 29);
        else
            dictMonths.Add(2, 28);
        dictMonths.Add(3, 31);
        dictMonths.Add(4, 30);
        dictMonths.Add(5, 31);
        dictMonths.Add(6, 30);
        dictMonths.Add(7, 31);
        dictMonths.Add(8, 31);
        dictMonths.Add(9, 30);
        dictMonths.Add(10, 31);
        dictMonths.Add(11, 30);
        dictMonths.Add(12, 31);

        //Time difference between dates
        TimeSpan span = futureDate - beforeDate;
        hours = span.Hours;
        minutes = span.Minutes;

        //Days total
        days = span.Days;
        //Find how many years
        DateTime zeroTime = new DateTime(1, 1, 1);

        // Because we start at year 1 for the Gregorian
        // calendar, we must subtract a year here.
        years = (zeroTime + span).Year - 1;
        //find difference of days of years already found
        int startYear = futureDate.Year - years;
        for (int i = 0; i < years; i++)
        {
            if (DateTime.IsLeapYear(startYear))
                days -= 366;
            else
                days -= 365;

            startYear++;
        }
        //Find months by multiplying months in year by difference of datetime years then add difference of current year months
        months = 12 * (futureDate.Year - beforeDate.Year) + (futureDate.Month - beforeDate.Month);
        //month may need to be decremented because the above calculates the ceiling of the months, not the floor.
        //to do so we increase before by the same number of months and compare.
        //(500ms fudge factor because datetimes are not precise enough to compare exactly)
        if (futureDate.CompareTo(beforeDate.AddMonths(months).AddMilliseconds(-500)) <= 0)
        {
            --months;
        }
        //subtract months from how many years we have already accumulated
        months -= (12 * years);
        //find how many days by compared to our month dictionary
        int startMonth = beforeDate.Month;
        for (int i = 0; i < months; i++)
        {
            //check if faulty leap year
            if (startMonth == 2 && (months - 1 > 10))
                days -= 28;
            else
                days -= dictMonths[startMonth];
            startMonth++;
            if (startMonth > 12)
            {
                startMonth = 1;
            }
        }
        //Find if any weeks are within our now total days
        weeks = days / 7;
        if (weeks > 0)
        {
            //remainder is days left
            days = days % 7;
        }

        Console.WriteLine(years + " " + months + " " + weeks + " " + days + " " + span.Hours + " " + span.Minutes);

        if (years > 0)
        {
            if (years > 1 && months > 1)
                return $"Latest Reply: {years} years, {months} months ago.";
            else if (years > 1 && months == 0)
                return $"Latest Reply: {years} years ago.";
            else if (years == 1 && months == 0)
                return $"Latest Reply: {years} year ago.";
            else if (years > 1)
                return $"Latest Reply: {years} years, {months} month ago.";
            else if (months > 1)
                return $"Latest Reply: {years} year, {months} months ago.";
            else
                return $"Latest Reply: {years} year, {months} month ago.";
        }
        else if (months > 0)
        {
            if (months > 1 && weeks > 1)
                return $"Latest Reply: {months} months, {weeks} weeks ago.";
            else if (months > 1 && weeks == 0)
                return $"Latest Reply: {months} months ago.";
            else if (months == 1 && weeks == 0)
                return $"Latest Reply: {months} month ago.";
            else if (months > 1)
                return $"Latest Reply: {months} months, {weeks} week ago.";
            else if (weeks > 1)
                return $"Latest Reply: {months} month, {weeks} weeks ago.";
            else
                return $"Latest Reply: {months} month, {weeks} week ago.";
        }
        else if (weeks > 0)
        {
            if (weeks > 1 && days > 1)
                return $"Latest Reply: {weeks} weeks, {days} days ago.";
            else if (weeks > 1 && days == 0)
                return $"Latest Reply: {weeks} weeks ago.";
            else if (weeks == 1 && days == 0)
                return $"Latest Reply: {weeks} week ago.";
            else if (weeks > 1)
                return $"Latest Reply: {weeks} weeks, {days} day ago.";
            else if (days > 1)
                return $"Latest Reply: {weeks} week, {days} days ago.";
            else
                return $"Latest Reply: {weeks} week, {days} day ago.";
        }
        else if (days > 0)
        {
            if (days > 1 && hours > 1)
                return $"Latest Reply: {days} days, {hours} hours ago.";
            else if (days > 1 && hours == 0)
                return $"Latest Reply: {days} days ago.";
            else if (days == 1 && hours == 0)
                return $"Latest Reply: {days} day ago.";
            else if (days > 1)
                return $"Latest Reply: {days} days, {hours} hour ago.";
            else if (hours > 1)
                return $"Latest Reply: {days} day, {hours} hours ago.";
            else
                return $"Latest Reply: {days} day, {hours} hour ago.";
        }
        else if (hours > 0)
        {
            if (hours > 1 && minutes > 1)
                return $"Latest Reply: {hours} hours, {minutes} minutes ago.";
            else if (hours > 1 && minutes == 0)
                return $"Latest Reply: {hours} hours ago.";
            else if (hours == 1 && minutes == 0)
                return $"Latest Reply: {hours} hour ago.";
            else if (hours > 1)
                return $"Latest Reply: {hours} hours, {minutes} minute ago.";
            else if (minutes > 1)
                return $"Latest Reply: {hours} hour, {minutes} minutes ago.";
            else
                return $"Latest Reply: {hours} hour, {minutes} minute ago.";
        }
        else if (minutes > 0)
        {
            if (minutes > 1)
                return $"Latest Reply: {minutes} minutes ago.";
            else
                return $"Latest Reply: {minutes} minute ago.";
        }
        else
        {
            return $"Latest Reply: Just now.";
        }

score 0 · Answer 11 · answered Jul 13 '21 at 12:41

It's quite an old question, but still time to have a go.

Important to consider that months have differing number of days.

    public static (int, int, int) GetYearsMonthsDaysDifference(DateTime date1, DateTime date2)
    {
        DateTime startDate = date1;
        DateTime endDate = date2;

        if (date1 > date2)
        {
            startDate = date2;
            endDate = date1;
        }

        var months = (endDate.Month + (12 - startDate.Month)) - (endDate.Day < startDate.Day ? 1 : 0);
        var years = (endDate.Year - startDate.Year - (months < 12 ? 1 : 0));
        months -= (months >= 12 ? 12 : 0);
        var days = endDate.DayOfYear - startDate.AddYears(years).AddMonths(months).DayOfYear;

        return (years, months, days);
    }

Calculate Years, Months, weeks and Days

11 Answers11

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