IRST to ICT
+3h 30mIRST
IRSTSOURCEICT
ICTGreen rows indicate typical business hours (9 AM - 5 PM)
IRST and ICT on the World Map
The map below highlights the IRST (Iran Standard Time) and ICT (Indochina Time) timezone regions across the globe.
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.
ICT – Indochina Time
UTC+07:00Indochina Time (ICT) is the time zone for Vietnam, Thailand, Laos, and Cambodia, 7 hours ahead of UTC.
- •Bangkok is one of the most visited cities in the world.
- •ICT is 12 hours ahead of EST.
- •Thailand, Vietnam, and Cambodia all share ICT.
Understanding the +3h 30m Gap: IRST vs ICT
IRST runs on Iran Standard Time (IRST) at UTC+03:30. ICT runs on Indochina Time (ICT) at UTC+07:00. That puts IRST 3 hours 30 minutes ahead of ICT — a difference of +3h 30m at the current offsets.
In practice, when it is 9:00 AM in IRST it is 12:30 PM in ICT. Midnight in IRST is 3:30 AM in ICT. Neither zone observes daylight saving time, so the offset between them stays constant all year.
IRST to ICT time conversion table
| IRST (IRST) | ICT (ICT) | Day |
|---|---|---|
| 12:00 AM | 3:30 AM | same day |
| 6:00 AM | 9:30 AM | same day |
| 7:00 AM | 10:30 AM | same day |
| 8:00 AM | 11:30 AM | same day |
| 9:00 AM | 12:30 PM | same day |
| 12:00 PM | 3:30 PM | same day |
| 3:00 PM | 6:30 PM | same day |
| 5:00 PM | 8:30 PM | same day |
| 6:00 PM | 9:30 PM | same day |
| 9:00 PM | 12:30 AM | next day |
Why people convert IRST to ICT time
- Scheduling a call from IRST to ICT: a 10:00 AM start in IRST lands at 1:30 PM in ICT, so you can confirm the slot without doing the arithmetic yourself.
- Finding shared working hours: both IRST and ICT are inside the 9-to-5 working day between 9:00 AM and 1:30 PM IRST time (12:30 PM–5:00 PM ICT). That is roughly 4 hours 30 minutes of usable overlap.
- Watching a live event or market open: IRST viewers need 12:30 PM in ICT to catch a 9:00 AM start there, and 8:30 PM if the event is anchored to IRST.
- Always state the zone abbreviation, not just the hour. "3:00 PM IRST" is unambiguous; "3 PM" across a +3h 30m gap is not.
- Block 9:00 AM–1:30 PM IRST as the recurring meeting window if you work primarily from IRST and need ICT colleagues present.
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.
About ICT (Indochina Time)
Indochina Time (ICT) is used across Southeast Asia including Vietnam, Thailand, Laos, and Cambodia. Indonesia (Western time, WIB) also uses UTC+07:00. ICT does not observe daylight saving time.
Best time to call between IRST and ICT
Both IRST and ICT sit inside the 9 AM – 5 PM working day between 9:00 AM–1:30 PM IRST, which is 12:30 PM–5:00 PM ICT. That gives roughly 4 hours and 30 minutes of shared time — the safest window for a live call or meeting.
Business hours overlap
IRST and ICT overlap for about 4 hours during the working day — enough for meetings if you avoid the edges of the window.
IRST is 3 hours 30 minutes ahead of ICT (IRST UTC+03:30 → ICT UTC+07:00). The shared working window is 9:00 AM–1:30 PM IRST. 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 IRST and ICT?
IRST (IRST, UTC+03:30) is 3 hours 30 minutes ahead of ICT (ICT, UTC+07:00). The gap is currently +3h 30m.
How do I convert IRST time to ICT time?
Add +3h 30m to IRST local time. For example, 9:00 AM in IRST is 12:30 PM in ICT.
What time is it in ICT right now?
ICT uses ICT at UTC+07:00. Use the live converter at the top of this page — it updates in real time and already accounts for the +3h 30m offset from IRST.
What is the best time to call ICT from IRST?
Call between 9:00 AM and 1:30 PM IRST — that maps to 12:30 PM–5:00 PM ICT and keeps both parties inside the working day.
Which is ahead, IRST or ICT?
IRST is 3 hours 30 minutes ahead of ICT. When it is 12:00 PM in IRST it is 3:30 PM in ICT.
Does daylight saving time affect the IRST–ICT difference?
Neither zone observes daylight saving time, so the +3h 30m offset between IRST and ICT is fixed all year.
Which other cities share IRST's time zone?
IRST also covers Tehran, Isfahan, Mashhad, Tabriz, Shiraz, Karaj.
Which countries use IRST, IRST's zone?
IRST is used in Iran.
Is there a day difference between IRST and ICT?
Not normally. The +3h 30m gap only pushes the date over for late-evening times.
What is the time difference between IRST and ICT?
ICT is +3h 30m from IRST.
What timezone is IRST in?
IRST operates on its local timezone.
What timezone is ICT in?
ICT operates on its local timezone.
Which countries use IRST (Iran Standard Time)?
IRST is used in Iran.
Does IRST observe daylight saving time?
Yes, IRST switches to IRDT during summer months.
What are some interesting facts about IRST?
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).
Which cities are in the ICT timezone?
Major cities in the ICT timezone include Bangkok, Ho Chi Minh City, Hanoi, Jakarta, Phnom Penh, Vientiane.
What is the UTC offset for ICT?
Indochina Time (ICT) is at UTC+07:00.
What should I know about the ICT timezone?
Bangkok is one of the most visited cities in the world. ICT is 12 hours ahead of EST.
When is it midnight in IRST, what time is it in ICT?
When it is 12:00 AM (midnight) in IRST (IRST), it is +3h 30m later in ICT (ICT).
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