KST to Tehran
-5h 30mKST
KSTSOURCETehran
IRSTGreen rows indicate typical business hours (9 AM - 5 PM)
KST and IRST on the World Map
The map below highlights the KST (Korea Standard Time) and IRST (Iran Standard Time) timezone regions across the globe.
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).
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 Tehran
WikipediaTehran operates on Iran Standard Time (IRST), UTC+3:30. Iran's unique half-hour offset makes Tehran time distinctive for regional business coordination.
Iran Standard Time (IRST) is one of few timezones with a 30-minute offset (UTC+3:30).
Time Conversion Guide: KST to Tehran
KST runs on Korea Standard Time (KST) at UTC+09:00. Tehran runs on Iran Standard Time (IRST) at UTC+03:30. That puts KST 5 hours 30 minutes behind Tehran — a difference of -5h 30m at the current offsets.
In practice, when it is 9:00 AM in KST it is 3:30 AM in Tehran. Midnight in KST is 6:30 PM in Tehran. Neither zone observes daylight saving time, so the offset between them stays constant all year.
KST to Tehran time conversion table
| KST (KST) | Tehran (IRST) | Day |
|---|---|---|
| 12:00 AM | 6:30 PM | previous day |
| 6:00 AM | 12:30 AM | same day |
| 7:00 AM | 1:30 AM | same day |
| 8:00 AM | 2:30 AM | same day |
| 9:00 AM | 3:30 AM | same day |
| 12:00 PM | 6:30 AM | same day |
| 3:00 PM | 9:30 AM | same day |
| 5:00 PM | 11:30 AM | same day |
| 6:00 PM | 12:30 PM | same day |
| 9:00 PM | 3:30 PM | same day |
Why people convert KST to Tehran time
- Scheduling a call from KST to Tehran: a 10:00 AM start in KST lands at 4:30 AM in Tehran, so you can confirm the slot without doing the arithmetic yourself.
- Finding shared working hours: both KST and Tehran are inside the 9-to-5 working day between 2:30 PM and 5:00 PM KST time (9:00 AM–11:30 AM IRST). That is roughly 2 hours 30 minutes of usable overlap.
- Coordinating a KST-based team with Tehran 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 KST" is unambiguous; "3 PM" across a -5h 30m gap is not.
- Block 2:30 PM–5:00 PM KST as the recurring meeting window if you work primarily from KST and need Tehran colleagues present.
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.
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 KST and Tehran
Both KST and Tehran sit inside the 9 AM – 5 PM working day between 2:30 PM–5:00 PM KST, which is 9:00 AM–11:30 AM IRST. That gives roughly 2 hours and 30 minutes of shared time — the safest window for a live call or meeting.
Business hours overlap
KST and Tehran overlap for about 2 hours during the working day — enough for meetings if you avoid the edges of the window.
KST is 5 hours 30 minutes behind Tehran (KST UTC+09:00 → IRST UTC+03:30). The shared working window is 2:30 PM–5:00 PM KST. 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 KST and Tehran?
KST (KST, UTC+09:00) is 5 hours 30 minutes behind Tehran (IRST, UTC+03:30). The gap is currently -5h 30m.
How do I convert KST time to Tehran time?
Add -5h 30m to KST local time. For example, 9:00 AM in KST is 3:30 AM in Tehran.
What time is it in Tehran right now?
Tehran 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 -5h 30m offset from KST.
What is the best time to call Tehran from KST?
Call between 2:30 PM and 5:00 PM KST — that maps to 9:00 AM–11:30 AM IRST and keeps both parties inside the working day.
Which is behind, KST or Tehran?
KST is 5 hours 30 minutes behind Tehran. When it is 12:00 PM in KST it is 6:30 AM in Tehran.
Do KST and Tehran use different time zones?
KST uses KST at UTC+09:00, while Tehran (Iran) uses IRST at UTC+03:30. The IANA identifiers are Asia/Seoul and Asia/Tehran.
Does daylight saving time affect the KST–Tehran difference?
Neither zone observes daylight saving time, so the -5h 30m offset between KST and Tehran is fixed all year.
Which other cities share KST's time zone?
KST also covers Seoul, Busan, Incheon, Daegu, Daejeon, Pyongyang.
Which countries use KST, KST's zone?
KST is used in South Korea, North Korea.
Is there a day difference between KST and Tehran?
Not normally. The -5h 30m gap only pushes the date over the previous day.
What is the time difference between KST and Tehran?
Tehran is -5h 30m from KST.
What timezone is KST in?
KST operates on its local timezone.
What timezone is Tehran in?
Tehran operates on Iran Standard Time (IRST), UTC+3:30. Iran's unique half-hour offset makes Tehran time distinctive for regional business coordination.
What are the business hours in Tehran?
Standard business hours in Tehran are 8:00 AM - 4:00 PM IRST.
Which countries use KST (Korea Standard Time)?
KST is used in South Korea, North Korea.
Does KST observe daylight saving time?
No, KST does not observe daylight saving time and remains at UTC+09:00 year-round.
What are some interesting facts about KST?
South Korea does not observe daylight saving time. Seoul is home to Samsung, LG, and Hyundai headquarters.
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 KST, what time is it in Tehran?
When it is 12:00 AM (midnight) in KST (KST), it is -5h 30m later in Tehran (IRST).
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