JST

JST most commonly refers to Japan Standard Time, the standard time used throughout Japan. It is nine hours ahead of Coordinated Universal Time (UTC+9) and is observed year-round, as Japan does not observe daylight saving time. The time signal is anchored to the mean solar time at 135 degrees east longitude, which aligns closely with the entire country’s timekeeping.

Across Japan, JST governs official timekeeping, railway and airline timetables, broadcasting schedules, and business hours. In daily life, clocks, calendars, and computer systems typically display times in JST, sometimes accompanied by the UTC offset for clarity.

Historically, Japan established a single national standard time in the late 19th century to synchronize clocks nationwide, replacing a patchwork of local times.

In computing and data contexts, JST is commonly used as a time zone label to denote Japan Standard Time in software libraries and databases.

It is important to distinguish JST from other time zones that share the same offset, such as Korea Standard Time, in contexts requiring geographic specificity.

Notes: In addition to timekeeping, JST may be used as an acronym for other terms in different fields, but this article addresses Japan Standard Time.