Hong Kong to IRST
-4h 30mHong Kong
HKTSOURCEIRST
IRSTGreen rows indicate typical business hours (9 AM - 5 PM)
HKT and IRST on the World Map
The map below highlights the HKT (Hong Kong Time) and IRST (Iran Standard Time) timezone regions across the globe.
HKT – Hong Kong Time
UTC+08:00Hong Kong Time (HKT, UTC+08:00) is the time zone for Hong Kong, 8 hours ahead of UTC.
- •Hong Kong does not observe daylight saving time and has kept UTC+08:00 since 1979.
- •HKT shares its offset with China Standard Time, Singapore Time and Philippine Time.
- •The Hong Kong Stock Exchange opens at 09:30 HKT.
- •Hong Kong Time does not change with the seasons, so its gap to other zones is fixed.
IRST – Iran Standard Time
UTC+03:30Iran Standard Time (IRST) is the time zone for Iran, 3 hours and 30 minutes ahead of UTC.
- •IRST is one of only a few time zones with a 30-minute offset.
- •Iran observes daylight saving time, switching to IRDT (UTC+04:30).
- •Tehran has a metropolitan population of over 16 million.
About Hong Kong
WikipediaHong Kong Time (HKT) is UTC+8 with no daylight saving. As a major financial gateway to China, Hong Kong trading hours overlap with European morning sessions.
The city has one of the world's most efficient and affordable public transit systems.
Understanding the -4h 30m Gap: Hong Kong vs IRST
Hong Kong runs on Hong Kong Standard Time (HKT) at UTC+08:00. IRST runs on Iran Standard Time (IRST) at UTC+03:30. That puts Hong Kong 4 hours 30 minutes behind IRST — a difference of -4h 30m at the current offsets.
In practice, when it is 9:00 AM in Hong Kong it is 4:30 AM in IRST. Midnight in Hong Kong is 7:30 PM in IRST. Neither zone observes daylight saving time, so the offset between them stays constant all year.
Hong Kong to IRST time conversion table
| Hong Kong (HKT) | IRST (IRST) | Day |
|---|---|---|
| 12:00 AM | 7:30 PM | previous day |
| 6:00 AM | 1:30 AM | same day |
| 7:00 AM | 2:30 AM | same day |
| 8:00 AM | 3:30 AM | same day |
| 9:00 AM | 4:30 AM | same day |
| 12:00 PM | 7:30 AM | same day |
| 3:00 PM | 10:30 AM | same day |
| 5:00 PM | 12:30 PM | same day |
| 6:00 PM | 1:30 PM | same day |
| 9:00 PM | 4:30 PM | same day |
Why people convert Hong Kong to IRST time
- Scheduling a call from Hong Kong to IRST: a 10:00 AM start in Hong Kong lands at 5:30 AM in IRST, so you can confirm the slot without doing the arithmetic yourself.
- Finding shared working hours: both Hong Kong and IRST are inside the 9-to-5 working day between 1:30 PM and 5:00 PM HKT time (9:00 AM–12:30 PM IRST). That is roughly 3 hours 30 minutes of usable overlap.
- Keeping family and friends in sync: knowing that 8:00 PM in Hong Kong is 3:30 PM in IRST makes it easy to avoid calling at 3 AM.
- Always state the zone abbreviation, not just the hour. "3:00 PM HKT" is unambiguous; "3 PM" across a -4h 30m gap is not.
- Block 1:30 PM–5:00 PM HKT as the recurring meeting window if you work primarily from Hong Kong and need IRST colleagues present.
About HKT (Hong Kong Time)
Hong Kong Time (HKT) is fixed at UTC+08:00 all year and does not observe daylight saving time. Hong Kong last used summer time in 1979 and has kept a single offset since. HKT shares the UTC+08:00 offset with China Standard Time, Singapore Time, Malaysian Time, Philippine Time and Australian Western Standard Time, but is listed separately because Hong Kong maintains its own timekeeping authority. As a major financial centre, Hong Kong's trading hours set the rhythm for markets across Asia, opening at 09:30 HKT which is 01:30 in London and 20:30 the previous evening in New York.
About IRST (Iran Standard Time)
Iran Standard Time (IRST) is one of the few time zones with a 30-minute offset. Iran observes daylight saving time (IRDT, UTC+04:30) from late March to late September. Tehran, the capital, is one of the largest cities in the Middle East.
Best time to call between Hong Kong and IRST
Both Hong Kong and IRST sit inside the 9 AM – 5 PM working day between 1:30 PM–5:00 PM HKT, which is 9:00 AM–12:30 PM IRST. That gives roughly 3 hours and 30 minutes of shared time — the safest window for a live call or meeting.
Business hours overlap
Hong Kong and IRST overlap for about 3 hours during the working day — enough for meetings if you avoid the edges of the window.
Hong Kong is 4 hours 30 minutes behind IRST (HKT UTC+08:00 → IRST UTC+03:30). The shared working window is 1:30 PM–5:00 PM HKT. 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 Hong Kong and IRST?
Hong Kong (HKT, UTC+08:00) is 4 hours 30 minutes behind IRST (IRST, UTC+03:30). The gap is currently -4h 30m.
How do I convert Hong Kong time to IRST time?
Add -4h 30m to Hong Kong local time. For example, 9:00 AM in Hong Kong is 4:30 AM in IRST.
What time is it in IRST right now?
IRST uses IRST at UTC+03:30. Use the live converter at the top of this page — it updates in real time and already accounts for the -4h 30m offset from Hong Kong.
What is the best time to call IRST from Hong Kong?
Call between 1:30 PM and 5:00 PM HKT — that maps to 9:00 AM–12:30 PM IRST and keeps both parties inside the working day.
Which is behind, Hong Kong or IRST?
Hong Kong is 4 hours 30 minutes behind IRST. When it is 12:00 PM in Hong Kong it is 7:30 AM in IRST.
Do Hong Kong and IRST use different time zones?
Hong Kong (Hong Kong) uses HKT at UTC+08:00, while IRST uses IRST at UTC+03:30. The IANA identifiers are Asia/Hong_Kong and Asia/Tehran.
Does daylight saving time affect the Hong Kong–IRST difference?
Neither zone observes daylight saving time, so the -4h 30m offset between Hong Kong and IRST is fixed all year.
Which other cities share Hong Kong's time zone?
HKT also covers Hong Kong, Kowloon, Tsuen Wan, Sha Tin.
Which countries use HKT, Hong Kong's zone?
HKT is used in Hong Kong SAR.
Is there a day difference between Hong Kong and IRST?
Not normally. The -4h 30m gap only pushes the date over the previous day.
What is the time difference between Hong Kong and IRST?
IRST is -4h 30m from Hong Kong.
What timezone is Hong Kong in?
Hong Kong Time (HKT) is UTC+8 with no daylight saving. As a major financial gateway to China, Hong Kong trading hours overlap with European morning sessions.
What timezone is IRST in?
IRST operates on its local timezone.
What are the business hours in Hong Kong?
Standard business hours in Hong Kong are 9:00 AM - 6:00 PM HKT.
Which countries use HKT (Hong Kong Time)?
HKT is used in Hong Kong SAR.
Does HKT observe daylight saving time?
No, HKT does not observe daylight saving time and remains at UTC+08:00 year-round.
What are some interesting facts about HKT?
Hong Kong does not observe daylight saving time and has kept UTC+08:00 since 1979. HKT shares its offset with China Standard Time, Singapore Time and Philippine Time.
Which cities are in the IRST timezone?
Major cities in the IRST timezone include Tehran, Isfahan, Mashhad, Tabriz, Shiraz, Karaj.
What is the UTC offset for IRST?
Iran Standard Time (IRST) is at UTC+03:30. During daylight saving time, it shifts to IRDT.
What should I know about the IRST timezone?
IRST is one of only a few time zones with a 30-minute offset. Iran observes daylight saving time, switching to IRDT (UTC+04:30).
When is it midnight in Hong Kong, what time is it in IRST?
When it is 12:00 AM (midnight) in Hong Kong (HKT), it is -4h 30m later in IRST (IRST).
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