Colombo to HST
-15h 30mColombo
ISTSOURCEHST
HSTGreen rows indicate typical business hours (9 AM - 5 PM)
IST and HST on the World Map
The map below highlights the IST (India Standard Time) and HST (Hawaii Standard Time) timezone regions across the globe.
IST – India Standard Time
UTC+05:30India Standard Time (IST) is the time zone for India and Sri Lanka, 5 hours and 30 minutes ahead of UTC.
- •India is 10 hours 30 minutes ahead of EST and 5 hours 30 minutes ahead of GMT.
- •India uses a single time zone despite spanning 30° of longitude.
- •IST is one of only a handful of time zones with a 30-minute offset.
- •IST is the most populous single time zone in the world with over 1.4 billion people.
- •The Bombay Stock Exchange (BSE) and National Stock Exchange (NSE) operate on IST.
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).
About Colombo
WikipediaColombo operates on Sri Lanka Time (SLST), UTC+5:30. Sharing India's timezone, Colombo is a key South Asian trade and tourism hub.
Sri Lanka Standard Time (SLST) uses UTC+5:30, same offset as India.
Colombo vs HST: Offsets, DST and Best Call Times
Colombo runs on India Standard Time (IST) at UTC+05:30. HST runs on Hawaii Standard Time (HST) at UTC-10:00. That puts Colombo 15 hours 30 minutes behind HST — a difference of -15h 30m at the current offsets.
In practice, when it is 9:00 AM in Colombo it is 5:30 PM in HST on the previous day. Midnight in Colombo is 8:30 AM in HST. Neither zone observes daylight saving time, so the offset between them stays constant all year.
Colombo to HST time conversion table
| Colombo (IST) | HST (HST) | Day |
|---|---|---|
| 12:00 AM | 8:30 AM | previous day |
| 6:00 AM | 2:30 PM | previous day |
| 7:00 AM | 3:30 PM | previous day |
| 8:00 AM | 4:30 PM | previous day |
| 9:00 AM | 5:30 PM | previous day |
| 12:00 PM | 8:30 PM | previous day |
| 3:00 PM | 11:30 PM | previous day |
| 5:00 PM | 1:30 AM | same day |
| 6:00 PM | 2:30 AM | same day |
| 9:00 PM | 5:30 AM | same day |
Why people convert Colombo to HST time
- Scheduling a call from Colombo to HST: a 10:00 AM start in Colombo lands at 6:30 PM in HST the previous day, so you can confirm the slot without doing the arithmetic yourself.
- Handling a -15h 30m gap: Colombo and HST 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 HST is 5:30 PM in Colombo.
- Coordinating a Colombo-based team with HST contacts: quoting times in the other side's local clock — not your own — removes the single biggest source of missed meetings.
- Always state the zone abbreviation, not just the hour. "3:00 PM IST" is unambiguous; "3 PM" across a -15h 30m gap is not.
- With a -15h 30m gap there is no shared 9-to-5 window, so alternate the early start: one week Colombo takes the early slot, the next week HST does.
About IST (India Standard Time)
India Standard Time (IST) is the time observed throughout India and Sri Lanka. It is based on the 82.5°E meridian, passing through Mirzapur in Uttar Pradesh. India uses a single time zone despite spanning roughly 30° of longitude, which has been debated. IST does not observe daylight saving time. India is the world's most populous country, making IST one of the most-used time zones globally. The IT outsourcing industry and call centers operate primarily on IST, making the EST-to-IST conversion one of the most searched timezone conversions.
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.
Best time to call between Colombo and HST
With a -15h 30m offset there is no overlap inside a normal 9 AM – 5 PM day. HST opens at 9:00 AM HST, which is 5:30 PM in Colombo, so real-time calls need an early-morning or late-evening slot on one side.
Business hours overlap
Colombo and HST have no shared working hours because of the -15h 30m gap. Teams need to alternate early starts or rely on asynchronous handovers.
Colombo is 15 hours 30 minutes behind HST (IST UTC+05:30 → HST UTC-10:00). 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 Colombo and HST?
Colombo (IST, UTC+05:30) is 15 hours 30 minutes behind HST (HST, UTC-10:00). The gap is currently -15h 30m.
How do I convert Colombo time to HST time?
Add -15h 30m to Colombo local time. For example, 9:00 AM in Colombo is 5:30 PM in HST (previous day).
What time is it in HST right now?
HST uses HST at UTC-10:00. Use the live converter at the top of this page — it updates in real time and already accounts for the -15h 30m offset from Colombo.
What is the best time to call HST from Colombo?
There is no shared working-hours window because of the -15h 30m gap. The closest option is 1:00 PM in Colombo, which is 9:30 PM in HST.
Which is behind, Colombo or HST?
Colombo is 15 hours 30 minutes behind HST. When it is 12:00 PM in Colombo it is 8:30 PM in HST.
Do Colombo and HST use different time zones?
Colombo (Sri Lanka) uses IST at UTC+05:30, while HST uses HST at UTC-10:00. The IANA identifiers are Asia/Colombo and Pacific/Honolulu.
Does daylight saving time affect the Colombo–HST difference?
Neither zone observes daylight saving time, so the -15h 30m offset between Colombo and HST is fixed all year.
Which other cities share Colombo's time zone?
IST also covers Mumbai, Delhi, Bangalore, Kolkata, Chennai, Hyderabad, Pune, Ahmedabad and 4 more.
Which countries use IST, Colombo's zone?
IST is used in India, Sri Lanka.
Is there a day difference between Colombo and HST?
Sometimes. The -15h 30m gap is large enough that 8:00 PM or later in Colombo already falls on the in HST.
What is the time difference between Colombo and HST?
HST is -15h 30m from Colombo.
What timezone is Colombo in?
Colombo operates on Sri Lanka Time (SLST), UTC+5:30. Sharing India's timezone, Colombo is a key South Asian trade and tourism hub.
What timezone is HST in?
HST operates on its local timezone.
What are the business hours in Colombo?
Standard business hours in Colombo are 9:00 AM - 5:00 PM IST.
Which countries use IST (India Standard Time)?
IST is used in India, Sri Lanka.
Does IST observe daylight saving time?
No, IST does not observe daylight saving time and remains at UTC+05:30 year-round.
What are some interesting facts about IST?
India is 10 hours 30 minutes ahead of EST and 5 hours 30 minutes ahead of GMT. India uses a single time zone despite spanning 30° of longitude.
Which cities are in the HST timezone?
Major cities in the HST timezone include Honolulu, Hilo, Kailua, Pearl City, Kapolei.
What is the UTC offset for HST?
Hawaii Standard Time (HST) is at UTC-10:00.
What should I know about the HST timezone?
Hawaii does not observe daylight saving time. HST is 5 hours behind EST in winter and 6 hours behind EDT in summer.
When is it midnight in Colombo, what time is it in HST?
When it is 12:00 AM (midnight) in Colombo (IST), it is -15h 30m later in HST (HST).
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