IST to JST Time Converter
JST is 3 hours and 30 minutes ahead of IST. IST is UTC+5:30, and JST is UTC+9:00.
Best Time to Call Between IST and JST
Both zones are inside normal business hours between 9:00 AM and 2:00 PM IST — that's 12:30 PM to 5:30 PM JST. That's a 5-hour window.
both at work IST only JST only neither — hours along the strip are IST.
Common Times Converted
IST on the left, JST on the right.
IST to JST: Full 24-Hour Conversion Table
Shaded rows are working hours; the darker shade marks the hours when both zones are at work.
| IST | JST | Working hours |
|---|---|---|
| 12:00 AM | 3:30 AM | — |
| 1:00 AM | 4:30 AM | — |
| 2:00 AM | 5:30 AM | — |
| 3:00 AM | 6:30 AM | — |
| 4:00 AM | 7:30 AM | — |
| 5:00 AM | 8:30 AM | — |
| 6:00 AM | 9:30 AM | JST only |
| 7:00 AM | 10:30 AM | JST only |
| 8:00 AM | 11:30 AM | JST only |
| 9:00 AM | 12:30 PM | Both zones |
| 10:00 AM | 1:30 PM | Both zones |
| 11:00 AM | 2:30 PM | Both zones |
| 12:00 PM | 3:30 PM | Both zones |
| 1:00 PM | 4:30 PM | Both zones |
| 2:00 PM | 5:30 PM | IST only |
| 3:00 PM | 6:30 PM | IST only |
| 4:00 PM | 7:30 PM | IST only |
| 5:00 PM | 8:30 PM | — |
| 6:00 PM | 9:30 PM | — |
| 7:00 PM | 10:30 PM | — |
| 8:00 PM | 11:30 PM | — |
| 9:00 PM | 12:30 AM next day | — |
| 10:00 PM | 1:30 AM next day | — |
| 11:00 PM | 2:30 AM next day | — |
What IST and JST Actually Are
IST — India Standard Time
Mumbai, Delhi, Bengaluru, Chennai, Kolkata, Hyderabad — and Colombo. Standing at UTC+5:30 as written, and the region does not change its clocks, so that offset holds all year. IST also stands for Irish Standard Time (UTC+1) and Israel Standard Time (UTC+2). This page covers the Indian one, which is by far the most searched.
India runs a single time zone across a country wide enough for two, which is why sunrise in the north-east can come nearly two hours before Mumbai's. Proposals for a second zone resurface regularly and have never been adopted.
JST — Japan Standard Time
Tokyo, Osaka, Yokohama, Nagoya, Sapporo. Standing at UTC+9:00 as written, and the region does not change its clocks, so that offset holds all year. Japan does not observe daylight saving, so this offset is fixed year-round.
Japan abolished daylight saving in 1952 and has resisted every attempt to reintroduce it, including a proposal around the 2020 Olympics.
What This Means in Practice
Expect times on the half hour
IST sits on a 30-minute offset rather than a whole hour, so a round number on one side is never a round number on the other. A 9:00 meeting becomes 30 minutes past the hour, which is exactly the detail calendar invitations get wrong when someone converts in their head.
A gap you can rely on
Neither region changes its clocks, so this difference holds every day of the year. A recurring meeting booked once stays correct — worth knowing, because most cross-border pairs cannot say that.
Major Cities in Each Zone
Cities on IST
Cities on JST
Frequently Asked Questions
What is the time difference between IST and JST?
JST is 3 hours and 30 minutes ahead of IST.
What is 9:00 AM IST in JST?
9:00 AM IST is 12:30 PM JST.
What are the best hours to schedule a call between IST and JST?
Between 9:00 AM and 2:00 PM IST, which is 12:30 PM to 5:30 PM JST. Both sides are inside normal business hours through that window.
Does the difference between IST and JST change during the year?
No. Neither region changes its clocks, so this gap is fixed all year round.
Does IST always mean India Standard Time?
IST also stands for Irish Standard Time (UTC+1) and Israel Standard Time (UTC+2). This page covers the Indian one, which is by far the most searched.
Does JST always mean Japan Standard Time?
Japan does not observe daylight saving, so this offset is fixed year-round.