HST to JST
+19hHST
HSTSOURCEJST
JSTGreen rows indicate typical business hours (9 AM - 5 PM)
HST and JST on the World Map
The map below highlights the HST (Hawaii Standard Time) and JST (Japan Standard Time) timezone regions across the globe.
HST – Hawaii Standard Time
UTC-10:00Hawaii Standard Time (HST) is the time zone for the Hawaiian Islands, 10 hours behind UTC.
- •Hawaii does not observe daylight saving time.
- •HST is 5 hours behind EST in winter and 6 hours behind EDT in summer.
- •Hawaii is one of only two US states that don't observe DST (the other is Arizona).
JST – Japan Standard Time
UTC+09:00Japan Standard Time (JST) is the time zone for Japan, 9 hours ahead of UTC.
- •Japan does not observe daylight saving time.
- •Tokyo is the most populous metropolitan area in the world.
- •The Tokyo Stock Exchange operates from 9:00 AM to 3:00 PM JST.
- •JST is 14 hours ahead of EST and 9 hours ahead of GMT.
Time Conversion Guide: HST to JST
HST runs on Hawaii Standard Time (HST) at UTC-10:00. JST runs on Japan Standard Time (JST) at UTC+09:00. That puts HST 19 hours ahead of JST — a difference of +19h at the current offsets.
In practice, when it is 9:00 AM in HST it is 4:00 AM in JST on the next day. Midnight in HST is 7:00 PM in JST. Neither zone observes daylight saving time, so the offset between them stays constant all year.
HST to JST time conversion table
| HST (HST) | JST (JST) | Day |
|---|---|---|
| 12:00 AM | 7:00 PM | same day |
| 6:00 AM | 1:00 AM | next day |
| 7:00 AM | 2:00 AM | next day |
| 8:00 AM | 3:00 AM | next day |
| 9:00 AM | 4:00 AM | next day |
| 12:00 PM | 7:00 AM | next day |
| 3:00 PM | 10:00 AM | next day |
| 5:00 PM | 12:00 PM | next day |
| 6:00 PM | 1:00 PM | next day |
| 9:00 PM | 4:00 PM | next day |
Why people convert HST to JST time
- Scheduling a call from HST to JST: a 10:00 AM start in HST lands at 5:00 AM in JST the next day, so you can confirm the slot without doing the arithmetic yourself.
- Handling a +19h gap: HST and JST have no overlap inside a normal 9-to-5 day, so real-time meetings need an early-morning or late-evening slot on one side. 9:00 AM in JST is 4:00 AM in HST.
- Keeping family and friends in sync: knowing that 8:00 PM in HST is 3:00 PM in JST makes it easy to avoid calling at 3 AM.
- Always state the zone abbreviation, not just the hour. "3:00 PM HST" is unambiguous; "3 PM" across a +19h gap is not.
- With a +19h gap there is no shared 9-to-5 window, so alternate the early start: one week HST takes the early slot, the next week JST does.
About HST (Hawaii Standard Time)
Hawaii Standard Time (HST) is used in the state of Hawaii and does not observe daylight saving time. This makes HST one of the most consistent time zones in the US. The Hawaiian Islands are among the last places on Earth to see a new calendar day.
About JST (Japan Standard Time)
Japan Standard Time (JST) is the standard time zone for all of Japan. Japan does not observe daylight saving time. JST is 9 hours ahead of UTC and 14 hours ahead of EST. The Tokyo Stock Exchange, the world's third largest by market capitalization, operates on JST. South Korea uses the same offset (KST) but it is a distinct time zone.
Best time to call between HST and JST
With a +19h offset there is no overlap inside a normal 9 AM – 5 PM day. JST opens at 9:00 AM JST, which is 4:00 AM in HST, so real-time calls need an early-morning or late-evening slot on one side.
Business hours overlap
HST and JST have no shared working hours because of the +19h gap. Teams need to alternate early starts or rely on asynchronous handovers.
HST is 19 hours ahead of JST (HST UTC-10:00 → JST UTC+09:00). There is no shared 9-to-5 window, so plan around an early or late slot. Remember to re-check around daylight-saving transitions.
Learn More About Time
Dive deeper into the fascinating world of timekeeping, time zones, and how they shape our global society:
Frequently Asked Questions
What is the time difference between HST and JST?
HST (HST, UTC-10:00) is 19 hours ahead of JST (JST, UTC+09:00). The gap is currently +19h.
How do I convert HST time to JST time?
Add +19h to HST local time. For example, 9:00 AM in HST is 4:00 AM in JST (next day).
What time is it in JST right now?
JST uses JST at UTC+09:00. Use the live converter at the top of this page — it updates in real time and already accounts for the +19h offset from HST.
What is the best time to call JST from HST?
There is no shared working-hours window because of the +19h gap. The closest option is 1:00 PM in HST, which is 8:00 AM in JST.
Which is ahead, HST or JST?
HST is 19 hours ahead of JST. When it is 12:00 PM in HST it is 7:00 AM in JST.
Does daylight saving time affect the HST–JST difference?
Neither zone observes daylight saving time, so the +19h offset between HST and JST is fixed all year.
Which other cities share HST's time zone?
HST also covers Honolulu, Hilo, Kailua, Pearl City, Kapolei.
Which countries use HST, HST's zone?
HST is used in United States (Hawaii).
Is there a day difference between HST and JST?
Sometimes. The +19h gap is large enough that 8:00 PM or later in HST already falls on the next day in JST.
What is the time difference between HST and JST?
JST is +19h from HST.
What timezone is HST in?
HST operates on its local timezone.
What timezone is JST in?
JST operates on its local timezone.
Which countries use HST (Hawaii Standard Time)?
HST is used in United States (Hawaii).
Does HST observe daylight saving time?
No, HST does not observe daylight saving time and remains at UTC-10:00 year-round.
What are some interesting facts about HST?
Hawaii does not observe daylight saving time. HST is 5 hours behind EST in winter and 6 hours behind EDT in summer.
Which cities are in the JST timezone?
Major cities in the JST timezone include Tokyo, Osaka, Yokohama, Nagoya, Sapporo, Kyoto, Kobe, Fukuoka.
What is the UTC offset for JST?
Japan Standard Time (JST) is at UTC+09:00.
What should I know about the JST timezone?
Japan does not observe daylight saving time. Tokyo is the most populous metropolitan area in the world.
When is it midnight in HST, what time is it in JST?
When it is 12:00 AM (midnight) in HST (HST), it is +19h later in JST (JST).
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