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TimeZoneInfo.AdjustmentRule.DaylightDelta Property

Gets the amount of time that is required to form the time zone's daylight saving time. This amount of time is added to the time zone's offset from Coordinated Universal Time (UTC).

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

member DaylightDelta : TimeSpan

Property Value

Type: System.TimeSpan
A TimeSpan object that indicates the amount of time to add to the standard time changes as a result of the adjustment rule.

The following formula defines a time zone's daylight saving time:

TimeZoneTime = BaseUtcOffset + DaylightDelta + UtcTime

The value of the DaylightDelta property can range from 14 hours to -14 hours.


   The DaylightDelta property measures the difference between the time zone’s standard time and its daylight saving time. It does not apply to changes in a time zone's standard offset from Coordinated Universal Time (UTC). To represent a time zone that has changed its standard time offset from UTC, you must call the CreateCustomTimeZone method to create a new time zone.

The most common value of the DaylightDelta property is 1.0 hours. The application of the daylight saving time adjustment rule increases the time zone's offset from Coordinated Universal Time (UTC) by one hour.

.NET Framework

Supported in: 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.