AddMilliseconds Method

DateTime.AddMilliseconds Method

[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]

Returns a new DateTime that adds the specified number of milliseconds to the value of this instance.

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)

Public Function AddMilliseconds ( _
	value As Double _
) As DateTime


Type: System.Double
The number of whole and fractional milliseconds to add. This value can be positive or negative, and is rounded to the nearest integer.

Return Value

Type: System.DateTime
An object whose value is the sum of the date and time represented by this instance and the number of milliseconds represented by value.


The resulting DateTime is earlier than DateTime.MinValue or later than DateTime.MaxValue.

This method does not change the value of this DateTime. Instead, a new DateTime is returned whose value is the result of this operation.

The fractional part of value is the fractional part of a millisecond. For example, 4.5 is equivalent to 4 milliseconds and 5000 ticks, where one millisecond = 10000 ticks.

The value parameter is rounded to the nearest integer.

The following example uses the AddMilliseconds method to add one millisecond and 1.5 milliseconds to a DateTime value. It then displays each new value and displays the difference between it and the original value. The difference is displayed both as a time span and as a number of ticks. The example makes it clear that one millisecond equals 10,000 ticks. It also shows that fractional milliseconds are rounded before performing the addition; the DateTime value that results from adding 1.5 milliseconds to the original date is 2 milliseconds greater than the original date.

Dim dateFormat As String = "MM/dd/yyyy hh:mm:ss.fffffff" 
Dim date1 As Date = #09/08/2010 16:00#
outputBlock.Text += String.Format("Original date: {0} ({1:N0} ticks)", _
                  date1.ToString(dateFormat), date1.Ticks) + Environment.NewLine
outputBlock.Text +=  Environment.NewLine

Dim date2 As Date = date1.AddMilliseconds(1)
outputBlock.Text += String.Format("Second date:   {0} ({1:N0} ticks)", _
                  date2.ToString(dateFormat), date2.Ticks) + Environment.NewLine
outputBlock.Text += String.Format("Difference between dates: {0} ({1:N0} ticks)", _
                  date2 - date1, date2.Ticks - date1.Ticks) + Environment.NewLine                        
outputBlock.Text +=  Environment.NewLine

Dim date3 As Date = date1.AddMilliseconds(1.5)
outputBlock.Text += String.Format("Third date:    {0} ({1:N0} ticks)", _
                  date3.ToString(dateFormat), date3.Ticks) + Environment.NewLine
outputBlock.Text += String.Format("Difference between dates: {0} ({1:N0} ticks)", _
                  date3 - date1, date3.Ticks - date1.Ticks) + Environment.NewLine                        
' The example displays the following output:
'    Original date: 09/08/2010 04:00:00.0000000 (634,195,584,000,000,000 ticks)
'    Second date:   09/08/2010 04:00:00.0010000 (634,195,584,000,010,000 ticks)
'    Difference between dates: 00:00:00.0010000 (10,000 ticks)
'    Third date:    09/08/2010 04:00:00.0020000 (634,195,584,000,020,000 ticks)
'    Difference between dates: 00:00:00.0020000 (20,000 ticks)      

Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Windows Phone

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