Eastern standard time (EST) is the time zone used by the eastern United States during the winter months. During the summer months, areas that normally observe eastern standard time move the clock forward one hour and observe eastern daylight time (EDT). You calculate eastern standard time by subtracting five hours from the Coordinated Universal Time (UTC) or the Greenwich Mean Time (GMT)
Determine the current UTC or GMT. Both UTC and GMT refer to the time at the Royal Observatory in Greenwich, London. For example, assume the current UTC or GMT is 4 pm.
Subtract five hours from the current UTC or GMT. Continuing the same example, 4 pm - five hours = 11 am. This time represents the current eastern standard time.
Adjust the current eastern standard time, as needed, for daylight savings. If the area you are in currently utilizes daylight savings time, then add one hour to the eastern standard time. Continuing the same example, 11 am + 1 hour = 12 pm. This time represents the current eastern daylight time.