Iran Standard Time (IRST), also called Iran Time (IRT), is a time zone used in Iran. The standard time is 3.5 hours ahead of Coordinated Universal Time (UTC+03:30). During its daylight saving time, it uses Iran Daylight Time (IRDT), which is 4.5 hours ahead of Coordinated Universal Time (UTC+04:30), but however, from 2006 to 2007, IRDT was not used in Iran, but was re-introduced on March 21, 2008.