DateTime.Add Method

May 11, 2014

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

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

public DateTime Add(
	TimeSpan value


Type: System.TimeSpan
The time interval to add. This value can be positive or negative.

Return Value

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


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

You can use the Add method to add more than one kind of time interval (days, hours, minutes, seconds, or milliseconds) in a single operation. This method's behavior is identical to that of the addition operator. The DateTime structure also supports specialized addition methods (such as AddDays, AddHours, and AddMinutes) for each time interval.

The Add method takes into account leap years and the number of days in a month when performing date arithmetic.

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 Kind property of the new DateTime instance is the same as that of the current instance.

The following example demonstrates the Add method. It calculates the day of the week that is 36 days (864 hours) from this moment.

// Calculate what day of the week is 36 days from this instant.
System.DateTime today = System.DateTime.Now;
System.TimeSpan duration = new System.TimeSpan(36, 0, 0, 0);
System.DateTime answer = today.Add(duration);
outputBlock.Text += String.Format("{0:dddd}", answer) + "\n";

Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Windows Phone

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