Asia/Hong_Kong

TZ identifier and aliases

Asia/Hong_Kong is the canonical identifier for Hong Kong Time. Hongkong (one word) is an older name still pointing at the same rules but is a deprecated alias — use Asia/Hong_Kong in new code.

UTC offset and DST rule

Asia/Hong_Kong is +08:00 year-round with no daylight saving time. Hong Kong observed DST for several extended periods through the 20th century but abolished it for good in 1979, and has kept a single fixed offset ever since.

Using it in cron, CI and Postgres

Set TZ=Asia/Hong_Kong for a process that should schedule by Hong Kong local time. Postgres accepts it via SET TIME ZONE 'Asia/Hong_Kong'; or the timezone setting. Because the offset never changes, a cron job's local-time schedule behaves identically every day of the year, with no DST boundary or skipped/duplicated local hour to plan around — a meaningful operational advantage for financial-sector scheduling in particular, given Hong Kong's role as a major stock exchange and settlement hub where precise, unambiguous timing matters.

History and quirks

Hong Kong first observed daylight saving in 1941, shortly before the Japanese occupation disrupted civil administration entirely, then resumed using it on and off through the 1950s, 60s and 70s under British colonial rule — a period when it was known locally as "Summer Time." Persistent public complaints about the disruption to sleep schedules and limited evidence of practical benefit led the government to drop it after 1979, and Hong Kong has run on fixed standard time through the handover to Chinese sovereignty in 1997 and up to today, regardless of mainland China's own time zone policy — Hong Kong maintains its own separate legal system and civil time under the "one country, two systems" framework, even though both Hong Kong and Beijing happen to share the same +08:00 offset. That shared offset is coincidental rather than mandated: Hong Kong's Basic Law makes no reference to synchronizing with mainland Chinese time specifically.

That legal separation matters more than the matching offset might suggest: because Hong Kong sets its own time zone policy independently, there's no structural guarantee it will always match Asia/Shanghai going forward, unlike Macau, which has likewise kept its own separate Asia/Macau identifier despite also sharing +08:00 today. Any system that assumes "Hong Kong" and "mainland China" can always share a single timezone constant, rather than two independently-tracked identifiers that currently happen to agree, is relying on a coincidence rather than a guarantee — worth keeping distinct in code even while the values match.

Offsets and DST transitions on this page are computed from the IANA time zone database bundled with your browser; the rules described above were verified against tzdata 2026b when this page was published.