Japan Standard Time, or JST, is 13 to 17 hours ahead of time zones in the 48 contiguous United States. During U.S. daylight savings time, Eastern Daylight Time, or EDT, is 13 hours behind JST. During standard time, Pacific Standard Time, or PST, is 17 hours behind JST.
JST encompasses all of Japan throughout the year. Most of the United States falls under four time zones, which are Eastern, Central, Mountain and Pacific. Therefore, time differences between the United States and Japan range from 13 and 16 hours behind JST during Daylight Savings time, which is from March to November, and 14 to 17 hours behind during Standard Time, which is from November to March.