Convert IRST to KST
KST is 5 hours 30 minutes ahead of IRST. IRST is UTC+3:30 and KST is UTC+9.
Right now: IRST · KST
Best time to schedule a meeting
Standard 9–5 working hours overlap for 3 hours: 9:00 AM–12:00 PM IRST (2:00 PM–5:00 PM KST). Schedule meetings inside that window.
| IRST | KST | Suitable? |
|---|---|---|
| 9:00 AM | 2:30 PM | working hours |
| 10:00 AM | 3:30 PM | working hours |
| 11:00 AM | 4:30 PM | working hours |
| 12:00 PM | 5:30 PM | outside 9–5 |
| 1:00 PM | 6:30 PM | outside 9–5 |
| 2:00 PM | 7:30 PM | outside 9–5 |
| 3:00 PM | 8:30 PM | outside 9–5 |
| 4:00 PM | 9:30 PM | outside 9–5 |
| 5:00 PM | 10:30 PM | outside 9–5 |
IRST to KST conversion table
| IRST | KST |
|---|---|
| 12:00 AM | 5:30 AM |
| 1:00 AM | 6:30 AM |
| 2:00 AM | 7:30 AM |
| 3:00 AM | 8:30 AM |
| 4:00 AM | 9:30 AM |
| 5:00 AM | 10:30 AM |
| 6:00 AM | 11:30 AM |
| 7:00 AM | 12:30 PM |
| 8:00 AM | 1:30 PM |
| 9:00 AM | 2:30 PM |
| 10:00 AM | 3:30 PM |
| 11:00 AM | 4:30 PM |
| 12:00 PM | 5:30 PM |
| 1:00 PM | 6:30 PM |
| 2:00 PM | 7:30 PM |
| 3:00 PM | 8:30 PM |
| 4:00 PM | 9:30 PM |
| 5:00 PM | 10:30 PM |
| 6:00 PM | 11:30 PM |
| 7:00 PM | 12:30 AM (next day) |
| 8:00 PM | 1:30 AM (next day) |
| 9:00 PM | 2:30 AM (next day) |
| 10:00 PM | 3:30 AM (next day) |
| 11:00 PM | 4:30 AM (next day) |
About IRST
Iran Standard Time (IRST) is UTC+3:30. It is used in Iran, all year.
Iran Standard Time is UTC+3:30. Iran ran daylight saving for decades and stopped in 2022, so material written before then puts the country half an hour further ahead in summer and is now wrong. Half-hour offsets are rare enough that scheduling tools sometimes round them, which turns a correct calculation into a thirty-minute error.
About KST
Korea Standard Time (KST) is UTC+9. It is used in South Korea, with no daylight saving.
Korea Standard Time is UTC+9, the same as Japan, and South Korea has had no daylight saving since 1988 when it was used for the Seoul Olympics. The two Koreas briefly differed: the North moved to UTC+8:30 in 2015 and returned to UTC+9 in 2018, which is the only time in modern history the peninsula ran on two clocks.
Does this gap change with the seasons?
Neither IRST nor KST shifts with the seasons, so this 5.5-hour difference holds all year. That is unusual enough to be worth relying on: most cross-continental gaps move twice a year.
This is the reason scheduling systems store an IANA zone such as Region/City rather than an offset or an abbreviation: the zone knows its own rules and the offset does not.
Frequently asked questions
What time is 9:00 AM IRST in KST?
9:00 AM IRST is 2:30 PM KST.
Is KST ahead of IRST?
KST is 5 hours 30 minutes ahead of IRST.
Which time zone does this use?
IRST is UTC+3:30 and KST is UTC+9. Both abbreviations denote a single fixed offset, so this conversion never shifts with daylight saving — what changes is which abbreviation a place is using at the time.