Convert JST to IRST
IRST is 5 hours 30 minutes behind JST. JST is UTC+9 and IRST is UTC+3:30.
Right now: JST · IRST
Best time to schedule a meeting
Standard 9–5 working hours overlap for 2 hours: 3:00 PM–5:00 PM JST (9:00 AM–11:00 AM IRST). Schedule meetings inside that window.
| JST | IRST | Suitable? |
|---|---|---|
| 9:00 AM | 3:30 AM | outside 9–5 |
| 10:00 AM | 4:30 AM | outside 9–5 |
| 11:00 AM | 5:30 AM | outside 9–5 |
| 12:00 PM | 6:30 AM | outside 9–5 |
| 1:00 PM | 7:30 AM | outside 9–5 |
| 2:00 PM | 8:30 AM | outside 9–5 |
| 3:00 PM | 9:30 AM | working hours |
| 4:00 PM | 10:30 AM | working hours |
| 5:00 PM | 11:30 AM | working hours |
JST to IRST conversion table
| JST | IRST |
|---|---|
| 12:00 AM | 6:30 PM (previous day) |
| 1:00 AM | 7:30 PM (previous day) |
| 2:00 AM | 8:30 PM (previous day) |
| 3:00 AM | 9:30 PM (previous day) |
| 4:00 AM | 10:30 PM (previous day) |
| 5:00 AM | 11:30 PM (previous day) |
| 6:00 AM | 12:30 AM |
| 7:00 AM | 1:30 AM |
| 8:00 AM | 2:30 AM |
| 9:00 AM | 3:30 AM |
| 10:00 AM | 4:30 AM |
| 11:00 AM | 5:30 AM |
| 12:00 PM | 6:30 AM |
| 1:00 PM | 7:30 AM |
| 2:00 PM | 8:30 AM |
| 3:00 PM | 9:30 AM |
| 4:00 PM | 10:30 AM |
| 5:00 PM | 11:30 AM |
| 6:00 PM | 12:30 PM |
| 7:00 PM | 1:30 PM |
| 8:00 PM | 2:30 PM |
| 9:00 PM | 3:30 PM |
| 10:00 PM | 4:30 PM |
| 11:00 PM | 5:30 PM |
About JST
Japan Standard Time (JST) is UTC+9. It is used in all of Japan, with no daylight saving.
Japan Standard Time is UTC+9 for the whole country and has had no daylight saving since 1951, when the occupation-era experiment was abandoned. Proposals to reintroduce it, most recently before the 2020 Olympics, have failed each time. The offset is shared with South Korea, so Tokyo and Seoul never differ by even a minute.
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.
Does this gap change with the seasons?
Neither JST nor IRST 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 JST in IRST?
9:00 AM JST is 3:30 AM IRST.
Is IRST ahead of JST?
IRST is 5 hours 30 minutes behind JST.
Which time zone does this use?
JST is UTC+9 and IRST is UTC+3:30. 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.