What Is HST?
HST stands for Hawaii-Aleutian Standard Time, a timezone at UTC-10:00 (10 hours behind Coordinated Universal Time) from Coordinated Universal Time. It is used in Hawaii (all islands, no DST), Aleutian Islands of Alaska (with DST caveat, see below). The IANA Time Zone Database, the authoritative global reference used by operating systems, programming languages, and web services, records this zone under the identifier Pacific/Honolulu. IANA identifiers are unambiguous: Pacific/Honolulu maps to exactly one timezone in the world, unlike the abbreviation HST, which is specific to this region. HST does not observe Daylight Saving Time: the UTC-10:00 offset is fixed year-round.
Hawaii Standard Time is defined by the 150th meridian west longitude (150°W). The official timekeeping authority is the US Naval Observatory (USNO). The IANA identifier Pacific/Honolulu is fixed permanently at UTC-10:00. The Aleutian Islands use America/Adak, which observes DST (HADT, UTC-09:00 in summer).
Current HST Time and Date
The clock above shows the current HST time: 00:47 on Friday, March 6, 2026. It is calculated using the browser's Intl.DateTimeFormat API with the IANA identifier Pacific/Honolulu, the same source your phone and laptop use for timezone conversions. The time updates every second. If you need a static reference, note that HST is always UTC-10:00 from UTC : it never observes Daylight Saving Time.
HST to UTC Conversion
To convert HST to UTC: add 10:00 to the HST time. Example: 09:00 HST = 19:00 UTC. In ISO 8601 format, a HST timestamp is written as 2026-03-06T00:47:00-10:00. This format is unambiguous and machine-readable, always prefer it over abbreviation-only notation for data exchange.
Cities in the HST Timezone
Major cities that observe HST (UTC-10:00) include:
These cities all share the IANA zone identifier Pacific/Honolulu (or a zone with the same current offset). Click any city link to see its live clock, DST status, and time difference from major world cities.
DST Transition Dates for HST
Hawaii-Aleutian Standard Time does not observe Daylight Saving Time. The offset is fixed at UTC-10:00 year-round. This makes HST one of the most predictable timezones for international scheduling, the offset you see today is the offset you will see in six months.
DST Variants: HST vs Standard Time
HST does not observe Daylight Saving Time. The UTC-10:00 offset applies every day of the year, no seasonal adjustment, no clock changes.
Why Timezone Abbreviations Are Ambiguous
ISO 8601, the international standard for date and time notation, does not define timezone abbreviations. IANA, which maintains the authoritative timezone database, uses geographic identifiers (America/New_York, Asia/Kolkata) rather than abbreviations. Abbreviations emerged from railway timetables and military communications in the 19th and early 20th centuries, before any international standardization effort.
The result is a patchwork. EST is used in North America for UTC-05:00 and in parts of Australia for UTC+10:00 or UTC+11:00. IST covers three different UTC offsets across three continents. CST applies to UTC-06:00 (US Central), UTC+08:00 (China), and UTC-05:00 (Cuba). Even GMT, seemingly the anchor, is used differently than UTC: GMT is a timezone designation specific to the UK and West Africa, while UTC is the mathematical standard maintained by atomic clocks. They share the same offset (UTC+00:00) but are not interchangeable in formal contexts.
Best practice: always write the numeric offset alongside the abbreviation (HST (UTC-10:00)) or use ISO 8601 format for machine-readable timestamps. For the IANA identifier, use Pacific/Honolulu.
Converting HST to Major World Timezones
Current conversions from HST (00:47) to other major timezones:
- New York (EST/EDT): 05:47 (UTC-05:00)
- London (GMT/BST): 10:47 (UTC+00:00)
- Dubai (GST): 14:47 (UTC+04:00)
- India (IST): 16:17 (UTC+05:30)
- Singapore (SGT): 18:47 (UTC+08:00)
- Tokyo (JST): 19:47 (UTC+09:00)
- Sydney (AEST/AEDT): 21:47 (UTC+11:00)