HST to SGT
+18hHST
HSTSOURCESGT
SGTGreen rows indicate typical business hours (9 AM - 5 PM)
HST and SGT on the World Map
The map below highlights the HST (Hawaii Standard Time) and SGT (Singapore 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).
SGT – Singapore Standard Time
UTC+08:00Singapore Standard Time (SGT) is the time zone for Singapore, 8 hours ahead of UTC.
- •Singapore uses UTC+08:00 despite being at about 104°E longitude (closer to UTC+07:00).
- •Singapore does not observe daylight saving time.
- •The Singapore Exchange (SGX) operates on SGT.
Everything You Need to Know About HST and SGT Time
HST runs on Hawaii Standard Time (HST) at UTC-10:00. SGT runs on Singapore Standard Time (SGT) at UTC+08:00. That puts HST 18 hours ahead of SGT — a difference of +18h at the current offsets.
In practice, when it is 9:00 AM in HST it is 3:00 AM in SGT on the next day. Midnight in HST is 6:00 PM in SGT. Neither zone observes daylight saving time, so the offset between them stays constant all year.
HST to SGT time conversion table
| HST (HST) | SGT (SGT) | Day |
|---|---|---|
| 12:00 AM | 6:00 PM | same day |
| 6:00 AM | 12:00 AM | next day |
| 7:00 AM | 1:00 AM | next day |
| 8:00 AM | 2:00 AM | next day |
| 9:00 AM | 3:00 AM | next day |
| 12:00 PM | 6:00 AM | next day |
| 3:00 PM | 9:00 AM | next day |
| 5:00 PM | 11:00 AM | next day |
| 6:00 PM | 12:00 PM | next day |
| 9:00 PM | 3:00 PM | next day |
Why people convert HST to SGT time
- Scheduling a call from HST to SGT: a 10:00 AM start in HST lands at 4:00 AM in SGT the next day, so you can confirm the slot without doing the arithmetic yourself.
- Handling a +18h gap: HST and SGT 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 SGT is 3:00 AM in HST.
- Keeping family and friends in sync: knowing that 8:00 PM in HST is 2:00 PM in SGT 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 +18h gap is not.
- With a +18h gap there is no shared 9-to-5 window, so alternate the early start: one week HST takes the early slot, the next week SGT 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 SGT (Singapore Standard Time)
Singapore Standard Time (SGT) is used in Singapore year-round. Singapore does not observe daylight saving time. Despite being geographically close to the UTC+07:00 zone, Singapore uses UTC+08:00 to align with major trading partners like China, Hong Kong, and Malaysia. Singapore is a major global financial hub.
Best time to call between HST and SGT
With a +18h offset there is no overlap inside a normal 9 AM – 5 PM day. SGT opens at 9:00 AM SGT, which is 3:00 AM in HST, so real-time calls need an early-morning or late-evening slot on one side.
Business hours overlap
HST and SGT have no shared working hours because of the +18h gap. Teams need to alternate early starts or rely on asynchronous handovers.
HST is 18 hours ahead of SGT (HST UTC-10:00 → SGT UTC+08:00). 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 SGT?
HST (HST, UTC-10:00) is 18 hours ahead of SGT (SGT, UTC+08:00). The gap is currently +18h.
How do I convert HST time to SGT time?
Add +18h to HST local time. For example, 9:00 AM in HST is 3:00 AM in SGT (next day).
What time is it in SGT right now?
SGT uses SGT at UTC+08:00. Use the live converter at the top of this page — it updates in real time and already accounts for the +18h offset from HST.
What is the best time to call SGT from HST?
There is no shared working-hours window because of the +18h gap. The closest option is 1:00 PM in HST, which is 7:00 AM in SGT.
Which is ahead, HST or SGT?
HST is 18 hours ahead of SGT. When it is 12:00 PM in HST it is 6:00 AM in SGT.
Does daylight saving time affect the HST–SGT difference?
Neither zone observes daylight saving time, so the +18h offset between HST and SGT 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 SGT?
Sometimes. The +18h gap is large enough that 8:00 PM or later in HST already falls on the next day in SGT.
What is the time difference between HST and SGT?
SGT is +18h from HST.
What timezone is HST in?
HST operates on its local timezone.
What timezone is SGT in?
SGT 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 SGT timezone?
Major cities in the SGT timezone include Singapore.
What is the UTC offset for SGT?
Singapore Standard Time (SGT) is at UTC+08:00.
What should I know about the SGT timezone?
Singapore uses UTC+08:00 despite being at about 104°E longitude (closer to UTC+07:00). Singapore does not observe daylight saving time.
When is it midnight in HST, what time is it in SGT?
When it is 12:00 AM (midnight) in HST (HST), it is +18h later in SGT (SGT).
Related Developer Tools
Explore more tools that work great with timezone conversions for international teams:
Related Timezone Conversions
More HST time conversions
- hst to honolulu
- hst to new york
- hst to london
- hst to dubai
- hst to tokyo
- hst to singapore
- hst to sydney
- hst to los angeles
- hst to paris
- hst to delhi
- hst to mumbai
- hst to berlin
- hst to hong kong
- hst to toronto
- hst to kathmandu
- new york to hst
- london to hst
- dubai to hst
- tokyo to hst
- singapore to hst
- sydney to hst
- los angeles to hst
- paris to hst
- delhi to hst
- mumbai to hst
- berlin to hst
- hong kong to hst
- toronto to hst
- kathmandu to hst
See every conversion from HST →·See every conversion from SGT →