Epoch to JST (Japan Standard Time)

Convert a Unix epoch timestamp to Japan Standard Time (JST, UTC+09:00) — seconds or milliseconds — right in your browser. No upload, no time API.

Japan uses one fixed zone, JST (UTC+9), all year — no DST switches to worry about.

Worked example

Epoch 1768478400 is the same instant everywhere — only the wall-clock reading changes:

Nominal offset for this zone: UTC+09:00.

Where epoch conversions go wrong

• Seconds vs milliseconds. A 10-digit number is seconds; 13 digits is milliseconds. Feeding milliseconds to something expecting seconds throws the date tens of thousands of years into the future — the single most common cause of a "year 55000" bug.
• The number itself carries no timezone. An epoch is a count from 1970-01-01T00:00:00Z. A zone only appears when you format it, which is why the same integer can look like two different clock times and still be correct.
• Offsets are not fixed for zones that observe DST. JST is listed at UTC+09:00, but for any zone with daylight saving the correct offset depends on the date being converted — not on today. Convert with the real timestamp rather than assuming a constant.
• Store UTC, localise at the edge. Keeping epoch or UTC in the database and converting only for display avoids most timezone bugs entirely, because there is exactly one moment of truth.

Other zones: UTC · IST · PST · EST · CST · GMT/BST · CET · AEST · KST

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