JST to IRST
-5h 30mJST
JSTSOURCEIRST
IRSTGreen rows indicate typical business hours (9 AM - 5 PM)
JST and IRST on the World Map
The map below highlights the JST (Japan Standard Time) and IRST (Iran Standard Time) timezone regions across the globe.
JST – Japan Standard Time
UTC+09:00Japan Standard Time (JST) is the time zone for Japan, 9 hours ahead of UTC.
- •Japan does not observe daylight saving time.
- •Tokyo is the most populous metropolitan area in the world.
- •The Tokyo Stock Exchange operates from 9:00 AM to 3:00 PM JST.
- •JST is 14 hours ahead of EST and 9 hours ahead of GMT.
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.
Everything You Need to Know About JST and IRST Time
JST runs on Japan Standard Time (JST) at UTC+09:00. IRST runs on Iran Standard Time (IRST) at UTC+03:30. That puts JST 5 hours 30 minutes behind IRST — a difference of -5h 30m at the current offsets.
In practice, when it is 9:00 AM in JST it is 3:30 AM in IRST. Midnight in JST is 6:30 PM in IRST. Neither zone observes daylight saving time, so the offset between them stays constant all year.
JST to IRST time conversion table
| JST (JST) | IRST (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 JST to IRST time
- Scheduling a call from JST to IRST: a 10:00 AM start in JST lands at 4:30 AM in IRST, so you can confirm the slot without doing the arithmetic yourself.
- Finding shared working hours: both JST and IRST are inside the 9-to-5 working day between 2:30 PM and 5:00 PM JST time (9:00 AM–11:30 AM IRST). That is roughly 2 hours 30 minutes of usable overlap.
- Booking travel or deliveries: tracking IRST local time against JST keeps pickup windows and arrival estimates honest across the -5h 30m offset.
- Always state the zone abbreviation, not just the hour. "3:00 PM JST" is unambiguous; "3 PM" across a -5h 30m gap is not.
- Block 2:30 PM–5:00 PM JST as the recurring meeting window if you work primarily from JST and need IRST colleagues present.
About JST (Japan Standard Time)
Japan Standard Time (JST) is the standard time zone for all of Japan. Japan does not observe daylight saving time. JST is 9 hours ahead of UTC and 14 hours ahead of EST. The Tokyo Stock Exchange, the world's third largest by market capitalization, operates on JST. South Korea uses the same offset (KST) but it is a distinct time zone.
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 JST and IRST
Both JST and IRST sit inside the 9 AM – 5 PM working day between 2:30 PM–5:00 PM JST, 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
JST and IRST overlap for about 2 hours during the working day — enough for meetings if you avoid the edges of the window.
JST is 5 hours 30 minutes behind IRST (JST UTC+09:00 → IRST UTC+03:30). The shared working window is 2:30 PM–5:00 PM JST. 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 JST and IRST?
JST (JST, UTC+09:00) is 5 hours 30 minutes behind IRST (IRST, UTC+03:30). The gap is currently -5h 30m.
How do I convert JST time to IRST time?
Add -5h 30m to JST local time. For example, 9:00 AM in JST is 3:30 AM in IRST.
What time is it in IRST right now?
IRST 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 JST.
What is the best time to call IRST from JST?
Call between 2:30 PM and 5:00 PM JST — that maps to 9:00 AM–11:30 AM IRST and keeps both parties inside the working day.
Which is behind, JST or IRST?
JST is 5 hours 30 minutes behind IRST. When it is 12:00 PM in JST it is 6:30 AM in IRST.
Does daylight saving time affect the JST–IRST difference?
Neither zone observes daylight saving time, so the -5h 30m offset between JST and IRST is fixed all year.
Which other cities share JST's time zone?
JST also covers Tokyo, Osaka, Yokohama, Nagoya, Sapporo, Kyoto, Kobe, Fukuoka and 1 more.
Which countries use JST, JST's zone?
JST is used in Japan.
Is there a day difference between JST and IRST?
Not normally. The -5h 30m gap only pushes the date over the previous day.
What is the time difference between JST and IRST?
IRST is -5h 30m from JST.
What timezone is JST in?
JST operates on its local timezone.
What timezone is IRST in?
IRST operates on its local timezone.
Which countries use JST (Japan Standard Time)?
JST is used in Japan.
Does JST observe daylight saving time?
No, JST does not observe daylight saving time and remains at UTC+09:00 year-round.
What are some interesting facts about JST?
Japan does not observe daylight saving time. Tokyo is the most populous metropolitan area in the world.
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 JST, what time is it in IRST?
When it is 12:00 AM (midnight) in JST (JST), it is -5h 30m later in IRST (IRST).
Related Developer Tools
Explore more tools that work great with timezone conversions for international teams:
Related Timezone Conversions
More JST time conversions
- jst to tokyo
- jst to osaka
- jst to japan
- jst to new york
- jst to london
- jst to dubai
- jst to singapore
- jst to sydney
- jst to los angeles
- jst to paris
- jst to delhi
- jst to mumbai
- jst to berlin
- jst to hong kong
- jst to toronto
- jst to kathmandu
- new york to jst
- london to jst
- dubai to jst
- tokyo to jst
- singapore to jst
- sydney to jst
- los angeles to jst
- paris to jst
- delhi to jst
- mumbai to jst
- berlin to jst
- hong kong to jst
- toronto to jst
- kathmandu to jst
See every conversion from JST →·See every conversion from IRST →