- 1). Determine if the jurisdiction you are calculating the time for uses daylight savings time. The U.S. federal government doesn't require U.S. states or territories to follow daylight saving time. The Virgin Islands, Arizona, American Samoa, Guam, Hawaii, Puerto Rico and the Northern Marianas Islands do not follow this tradition. All other states and territories do.
- 2). Determine the right time and date to calculate the time change. Daylight savings time starts on the second Sunday in March at 2 a.m. local time. It ends on the first Sunday in November at 2 a.m. local time.
- 3). Add one hour to your current clock's time once you have reached the proper time and date and are doing it for a jurisdiction that follows this tradition.
Source...