Find the number of months between two dates in C#

DateTime d1 = new DateTime(2020, 1, 1);
DateTime d2 = new DateTime(2020,12,31);

// subtract the dates, and divide the total days by 30.4 (avg number of days per month)
int months = (int)(Math.Floor(((d2-d1).TotalDays / 30.4)));

Nasty way but does what I need (calculate physical calender months between two dates)

//2 datetimepicker controls dtpStart & dtpEnd

DateTime sdt = dtpStart.Value;
DateTime edt = dtpEnd.Value;
int numMonths = 0;
while(sdt < edt)
{
sdt = sdt.AddMonths(1);
numMonths++;
}