HKT to IRST
-4h 30mHKT
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.
Comparing Time Zones: HKT and IRST
HKT runs on Hong Kong Time (HKT) at UTC+08:00. IRST runs on Iran Standard Time (IRST) at UTC+03:30. That puts HKT 4 hours 30 minutes behind IRST — a difference of -4h 30m at the current offsets.
In practice, when it is 9:00 AM in HKT it is 4:30 AM in IRST. Midnight in HKT is 7:30 PM in IRST. Neither zone observes daylight saving time, so the offset between them stays constant all year.
HKT to IRST time conversion table
| HKT (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 HKT to IRST time
- Scheduling a call from HKT to IRST: a 10:00 AM start in HKT lands at 5:30 AM in IRST, so you can confirm the slot without doing the arithmetic yourself.
- Finding shared working hours: both HKT 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.
- Coordinating a HKT-based team with IRST 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 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 HKT 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 HKT and IRST
Both HKT 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
HKT and IRST overlap for about 3 hours during the working day — enough for meetings if you avoid the edges of the window.
HKT 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 HKT and IRST?
HKT (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 HKT time to IRST time?
Add -4h 30m to HKT local time. For example, 9:00 AM in HKT 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 HKT.
What is the best time to call IRST from HKT?
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, HKT or IRST?
HKT is 4 hours 30 minutes behind IRST. When it is 12:00 PM in HKT it is 7:30 AM in IRST.
Does daylight saving time affect the HKT–IRST difference?
Neither zone observes daylight saving time, so the -4h 30m offset between HKT and IRST is fixed all year.
Which other cities share HKT's time zone?
HKT also covers Hong Kong, Kowloon, Tsuen Wan, Sha Tin.
Which countries use HKT, HKT's zone?
HKT is used in Hong Kong SAR.
Is there a day difference between HKT and IRST?
Not normally. The -4h 30m gap only pushes the date over the previous day.
What is the time difference between HKT and IRST?
IRST is -4h 30m from HKT.
What timezone is HKT in?
HKT operates on its local timezone.
What timezone is IRST in?
IRST operates on its local timezone.
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 HKT, what time is it in IRST?
When it is 12:00 AM (midnight) in HKT (HKT), it is -4h 30m later in IRST (IRST).
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See every conversion from HKT →·See every conversion from IRST →