IRST to Seoul
+5h 30mIRST
IRSTSOURCESeoul
KSTGreen rows indicate typical business hours (9 AM - 5 PM)
IRST and KST on the World Map
The map below highlights the IRST (Iran Standard Time) and KST (Korea Standard 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.
KST – Korea Standard Time
UTC+09:00Korea Standard Time (KST) is the time zone for South Korea, 9 hours ahead of UTC.
- •South Korea does not observe daylight saving time.
- •Seoul is home to Samsung, LG, and Hyundai headquarters.
- •KST is the same offset as JST (UTC+09:00).
About Seoul
WikipediaSeoul operates on Korea Standard Time (KST), UTC+9, same as Japan. As a global tech and entertainment hub, Seoul coordinates with East Asian markets.
Seoul has the fastest average internet speed in the world.
IRST vs Seoul: Offsets, DST and Best Call Times
IRST runs on Iran Standard Time (IRST) at UTC+03:30. Seoul runs on Korean Standard Time (KST) at UTC+09:00. That puts IRST 5 hours 30 minutes ahead of Seoul — a difference of +5h 30m at the current offsets.
In practice, when it is 9:00 AM in IRST it is 2:30 PM in Seoul. Midnight in IRST is 5:30 AM in Seoul. Neither zone observes daylight saving time, so the offset between them stays constant all year.
IRST to Seoul time conversion table
| IRST (IRST) | Seoul (KST) | Day |
|---|---|---|
| 12:00 AM | 5:30 AM | same day |
| 6:00 AM | 11:30 AM | same day |
| 7:00 AM | 12:30 PM | same day |
| 8:00 AM | 1:30 PM | same day |
| 9:00 AM | 2:30 PM | same day |
| 12:00 PM | 5:30 PM | same day |
| 3:00 PM | 8:30 PM | same day |
| 5:00 PM | 10:30 PM | same day |
| 6:00 PM | 11:30 PM | same day |
| 9:00 PM | 2:30 AM | next day |
Why people convert IRST to Seoul time
- Scheduling a call from IRST to Seoul: a 10:00 AM start in IRST lands at 3:30 PM in Seoul, so you can confirm the slot without doing the arithmetic yourself.
- Finding shared working hours: both IRST and Seoul are inside the 9-to-5 working day between 9:00 AM and 11:30 AM IRST time (2:30 PM–5:00 PM KST). That is roughly 2 hours 30 minutes of usable overlap.
- Keeping family and friends in sync: knowing that 8:00 PM in IRST is 1:30 AM in Seoul makes it easy to avoid calling at 3 AM.
- Always state the zone abbreviation, not just the hour. "3:00 PM IRST" is unambiguous; "3 PM" across a +5h 30m gap is not.
- Block 9:00 AM–11:30 AM IRST as the recurring meeting window if you work primarily from IRST and need Seoul 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 KST (Korea Standard Time)
Korea Standard Time (KST) is the time zone used in South Korea. It shares the same UTC offset as Japan Standard Time but is a distinct time zone. South Korea does not observe daylight saving time. Seoul, the capital, is a major global tech and business hub.
Best time to call between IRST and Seoul
Both IRST and Seoul sit inside the 9 AM – 5 PM working day between 9:00 AM–11:30 AM IRST, which is 2:30 PM–5:00 PM KST. That gives roughly 2 hours and 30 minutes of shared time — the safest window for a live call or meeting.
Business hours overlap
IRST and Seoul overlap for about 2 hours during the working day — enough for meetings if you avoid the edges of the window.
IRST is 5 hours 30 minutes ahead of Seoul (IRST UTC+03:30 → KST UTC+09:00). The shared working window is 9:00 AM–11:30 AM 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 Seoul?
IRST (IRST, UTC+03:30) is 5 hours 30 minutes ahead of Seoul (KST, UTC+09:00). The gap is currently +5h 30m.
How do I convert IRST time to Seoul time?
Add +5h 30m to IRST local time. For example, 9:00 AM in IRST is 2:30 PM in Seoul.
What time is it in Seoul right now?
Seoul uses KST at UTC+09:00. Use the live converter at the top of this page — it updates in real time and already accounts for the +5h 30m offset from IRST.
What is the best time to call Seoul from IRST?
Call between 9:00 AM and 11:30 AM IRST — that maps to 2:30 PM–5:00 PM KST and keeps both parties inside the working day.
Which is ahead, IRST or Seoul?
IRST is 5 hours 30 minutes ahead of Seoul. When it is 12:00 PM in IRST it is 5:30 PM in Seoul.
Do IRST and Seoul use different time zones?
IRST uses IRST at UTC+03:30, while Seoul (South Korea) uses KST at UTC+09:00. The IANA identifiers are Asia/Tehran and Asia/Seoul.
Does daylight saving time affect the IRST–Seoul difference?
Neither zone observes daylight saving time, so the +5h 30m offset between IRST and Seoul 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 Seoul?
Not normally. The +5h 30m gap only pushes the date over for late-evening times.
What is the time difference between IRST and Seoul?
Seoul is +5h 30m from IRST.
What timezone is IRST in?
IRST operates on its local timezone.
What timezone is Seoul in?
Seoul operates on Korea Standard Time (KST), UTC+9, same as Japan. As a global tech and entertainment hub, Seoul coordinates with East Asian markets.
What are the business hours in Seoul?
Standard business hours in Seoul are 9:00 AM - 6:00 PM KST.
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 KST timezone?
Major cities in the KST timezone include Seoul, Busan, Incheon, Daegu, Daejeon, Pyongyang.
What is the UTC offset for KST?
Korea Standard Time (KST) is at UTC+09:00.
What should I know about the KST timezone?
South Korea does not observe daylight saving time. Seoul is home to Samsung, LG, and Hyundai headquarters.
When is it midnight in IRST, what time is it in Seoul?
When it is 12:00 AM (midnight) in IRST (IRST), it is +5h 30m later in Seoul (KST).
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