Calculate the number of months between two dates with C#

Say you’d like to calculate the difference between two dates in terms of number of months.

The following simple function will do just that: return the absolute number of months between two dates:

public static int GetMonthDifference(DateTime startDate, DateTime endDate)
	int monthsApart = 12 * (startDate.Year - endDate.Year) + startDate.Month - endDate.Month;
	return Math.Abs(monthsApart);


DateTime now = DateTime.UtcNow;
DateTime past = now.AddMonths(-13);
int monthDiff = GetMonthDifference(now, past);

monthDiff will be 13 as expected, i.e. not -13.

View all various C# language feature related posts here.


About Andras Nemes
I'm a .NET/Java developer living and working in Stockholm, Sweden.

2 Responses to Calculate the number of months between two dates with C#

  1. Pingback: Calculate the number of months between two dates with C# | Dinesh Ram Kali.

  2. Brian says:

    Excellent. Thank you for this. I was using someone’s code that calculated it incorrectly!

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