IST to HST Converter
Convert time between India Standard Time (IST) and Hawaii Standard Time (HST)
India Standard Time (IST)
Hawaii Standard Time (HST)
Time Difference
Hawaii Standard Time (HST) is 0 hours ahead of India Standard Time (IST)
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Select Time
Quick Reference
| IST | HST |
|---|---|
| 07:30 | 16:00 |
| 09:30 | 18:00 |
| 11:30 | 20:00 |
| 13:30 | 22:00 |
| 15:30 | 00:00 |
| 17:30 | 02:00 |
| 19:30 | 04:00 |
| 21:30 | 06:00 |
| 23:30 | 08:00 |
| 01:30 | 10:00 |
| 03:30 | 12:00 |
| 05:30 | 14:00 |
Top 10 Most Common Time Zones
| Abbreviation | Full Name | UTC Offset | Typical Use |
|---|---|---|---|
| UTC | Coordinated Universal Time | UTC ±0 | Global reference standard (servers, logs, APIs) |
| EST / EDT | Eastern (US) Time | UTC −5 / −4 | New York, Toronto — North American business hub |
| CST / CDT | Central (US) Time | UTC −6 / −5 | Chicago, Dallas — US central business region |
| PST / PDT | Pacific (US) Time | UTC −8 / −7 | San Francisco, Los Angeles — tech industry standard |
| GMT / BST | Greenwich Mean / British Summer Time | UTC 0 / +1 | UK, used globally as a reference with UTC |
| CET / CEST | Central European (Summer) Time | UTC +1 / +2 | Paris, Berlin, Amsterdam — EU business core |
| IST | India Standard Time | UTC +5:30 | India — major IT & outsourcing region |
| CST | China Standard Time | UTC +8 | Beijing, Shanghai — East Asia business hub |
| JST | Japan Standard Time | UTC +9 | Tokyo — finance & tech hub |
| AEST / AEDT | Australian Eastern (Daylight) Time | UTC +10 / +11 | Sydney, Melbourne — APAC regional business |
Why Time Zone Abbreviations Are Ambiguous
Unlike standardized identifiers (like America/New_York or Europe/London from the IANA tz database), abbreviations such as "CST" or "IST" are not globally unique. They can refer to different time zones depending on context — country, region, or even time of year (due to daylight saving time).
Common Ambiguous Time Zone Abbreviations
| Abbrev. | Common Meaning(s) | UTC Offset | Region(s) |
|---|---|---|---|
| CST | Central Standard Time / China Standard Time / Cuba Standard Time | UTC−6 / UTC+8 / UTC−5 | North America, China, Cuba |
| IST | Indian Standard Time / Irish Standard Time / Israel Standard Time | UTC+5:30 / UTC+1 / UTC+2 | India, Ireland, Israel |
| AST | Atlantic Standard Time / Arabia Standard Time | UTC−4 / UTC+3 | Caribbean, Canada, Middle East |
| PST | Pacific Standard Time / Philippine Standard Time | UTC−8 / UTC+8 | North America, Philippines |
| EST | Eastern Standard Time (North America / Australia) | UTC−5 / UTC+10 | North America, Australia |
✅ Best Practice
To avoid ambiguity, always:
- Use IANA tz identifiers — e.g.,
America/New_Yorkinstead of "EST" - Specify UTC offset explicitly — e.g.,
UTC−5when abbreviations must be used - Include the full timezone name — e.g., "Eastern Standard Time (EST)" with UTC offset
Related Time Zone Conversions
About IST to HST Time Conversion
Converting time between India Standard Time (IST) and Hawaii Standard Time (HST) is essential for coordinating between India and Hawaii. IST is UTC+5:30 (consistent year-round, no daylight saving time), while HST is UTC-10 (year-round, Hawaii does not observe daylight saving time). IST is 15.5 hours ahead of HST.
This conversion is important for Indian companies coordinating with Hawaii offices, tourism companies, tech startups, and international organizations with presence in Hawaii. The 15.5-hour offset is one of the largest among US timezones, creating significant scheduling challenges. Unlike most US states, Hawaii does not observe daylight saving time, making HST consistently 15.5 hours behind IST throughout the year. This extreme time difference requires careful planning and often necessitates asynchronous communication or shift-based work arrangements for India-Hawaii teams. Understanding this timezone relationship is crucial for managing expectations and enabling effective global operations.
Common Use Cases for IST to HST Conversion
Business & Work
- Scheduling calls between Indian offices and Hawaii-based companies
- Coordinating tourism and hospitality operations across India and Hawaii
- Managing international business operations with Hawaii headquarters
- Planning asynchronous handoff operations for 24-hour coverage
Personal & Travel
- Coordinating with family and friends in Hawaii
- Planning travel between India and Hawaii destinations
- Scheduling virtual meetings with Hawaii-based relatives
- Arranging online collaboration with Hawaii-based colleagues
Time Zone Information
India Standard Time (IST)
- UTC Offset: UTC+5:30
- IANA Timezone: Asia/Kolkata
- Daylight Saving: No daylight saving time (consistent year-round)
- Major Cities: New Delhi, Mumbai, Bangalore, Hyderabad, Chennai, Kolkata
- Coverage: Entire India (single timezone covering entire nation)
Hawaii Standard Time (HST)
- UTC Offset: UTC-10
- IANA Timezone: Pacific/Honolulu
- Daylight Saving: No daylight saving time (consistent year-round)
- Major Cities: Honolulu, Hilo, Kailua, Kaneohe, Mililani
- Coverage: Hawaii (all islands year-round)
Quick Reference: IST to HST
Remember: IST is always 15.5 hours ahead of HST. Hawaii does not observe daylight saving time, making this offset consistent throughout the year.
Frequently Asked Questions
What is the time difference between IST and HST?
India Standard Time (IST) is UTC+5:30, while Hawaii Standard Time (HST) is UTC-10. This means IST is 15.5 hours ahead of HST. When you have 12:00 PM in Honolulu (HST), it's 3:30 AM the next day in India (IST).
Does Hawaii observe daylight saving time like other US states?
No, Hawaii does not observe daylight saving time. Hawaii Standard Time (HST) remains UTC-10 throughout the year, making it one of the few US states that doesn't change its clocks. This means IST is consistently 15.5 hours ahead of HST year-round.
How does the IST to HST offset compare to other US timezones?
HST is the most behind of any US state timezone. IST is 15.5 hours ahead of HST, compared to 10.5 hours ahead of CDT (Central) and 9.5 hours ahead of EDT (Eastern). This makes Hawaii the most challenging timezone for real-time coordination with India, with minimal business hour overlap.
What are the best times to schedule calls between India and Hawaii?
Business hour overlap is extremely limited due to the 15.5-hour difference. Early morning in India (5-7 AM IST) overlaps with late evening in Hawaii (3:30-5:30 PM HST). Evening in India (8-10 PM IST) overlaps with early morning in Hawaii (4:30-6:30 AM HST). These windows are quite narrow for business coordination.
Why is the time difference 15.5 hours instead of a whole number?
India uses UTC+5:30, which has a 30-minute offset from standard UTC. This unique offset combined with Hawaii's UTC-10 creates the 15.5-hour difference. India is one of only a few countries that uses a 30-minute offset, making its conversions with many other timezones fractional.
Are there any businesses that coordinate between India and Hawaii?
Yes, several industries have operations across India and Hawaii: tourism and hospitality companies, tech startups with distributed teams, BPO services, and international organizations. These businesses often use asynchronous communication and shift work to manage the large time difference effectively.
Pro Tips
- • HST is UTC-10 year-round with no daylight saving time - it's one of the most consistent timezones globally. Mark this difference clearly in your calendar apps.
- • The 15.5-hour difference means a morning call in India is evening in Hawaii the previous day. Always verify the date when scheduling calls across this timezone.
- • For critical India-Hawaii communication, consider early morning India time (5-7 AM IST) for late evening Hawaii slots (3:30-5:30 PM HST) when both parties might still be working.
- • Asynchronous communication via email, recorded video messages, and shared documents works better than live calls for India-Hawaii coordination due to the minimal overlap window.
- • Hawaii's lack of daylight saving time makes it the simplest US timezone for long-term scheduling - no need to adjust for seasonal changes like other states.
- • If your team spans India and Hawaii, consider rotating shifts or having a third location (like US mainland) as a communication hub to maximize coverage.
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