IST to GST Time Converter
GST is 1 hour and 30 minutes behind IST. IST is UTC+5:30, and GST is UTC+4:00.
Best Time to Call Between IST and GST
Both zones are inside normal business hours between 11:00 AM and 5:00 PM IST — that's 9:30 AM to 3:30 PM GST. That's a 6-hour window.
both at work IST only GST only neither — hours along the strip are IST.
Common Times Converted
IST on the left, GST on the right.
IST to GST: Full 24-Hour Conversion Table
Shaded rows are working hours; the darker shade marks the hours when both zones are at work.
| IST | GST | Working hours |
|---|---|---|
| 12:00 AM | 10:30 PM prev day | — |
| 1:00 AM | 11:30 PM prev day | — |
| 2:00 AM | 12:30 AM | — |
| 3:00 AM | 1:30 AM | — |
| 4:00 AM | 2:30 AM | — |
| 5:00 AM | 3:30 AM | — |
| 6:00 AM | 4:30 AM | — |
| 7:00 AM | 5:30 AM | — |
| 8:00 AM | 6:30 AM | — |
| 9:00 AM | 7:30 AM | IST only |
| 10:00 AM | 8:30 AM | IST only |
| 11:00 AM | 9:30 AM | Both zones |
| 12:00 PM | 10:30 AM | Both zones |
| 1:00 PM | 11:30 AM | Both zones |
| 2:00 PM | 12:30 PM | Both zones |
| 3:00 PM | 1:30 PM | Both zones |
| 4:00 PM | 2:30 PM | Both zones |
| 5:00 PM | 3:30 PM | GST only |
| 6:00 PM | 4:30 PM | GST only |
| 7:00 PM | 5:30 PM | — |
| 8:00 PM | 6:30 PM | — |
| 9:00 PM | 7:30 PM | — |
| 10:00 PM | 8:30 PM | — |
| 11:00 PM | 9:30 PM | — |
What IST and GST 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.
GST — Gulf Standard Time
Dubai, Abu Dhabi, Sharjah, Muscat. Standing at UTC+4:00 as written, and the region does not change its clocks, so that offset holds all year. GST also refers to South Georgia Time (UTC-2), which you are very unlikely to want.
The Gulf states have never observed daylight saving, so Dubai's offset has been unchanged for decades — unusual stability for a region that grew as fast as it did.
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.
Close enough to share a working day
At only 1 hour and 30 minutes apart, the two working days overlap almost completely. Scheduling is barely constrained by the difference.
Major Cities in Each Zone
Cities on IST
Cities on GST
Frequently Asked Questions
What is the time difference between IST and GST?
GST is 1 hour and 30 minutes behind IST.
What is 9:00 AM IST in GST?
9:00 AM IST is 7:30 AM GST.
What are the best hours to schedule a call between IST and GST?
Between 11:00 AM and 5:00 PM IST, which is 9:30 AM to 3:30 PM GST. Both sides are inside normal business hours through that window.
Does the difference between IST and GST 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 GST always mean Gulf Standard Time?
GST also refers to South Georgia Time (UTC-2), which you are very unlikely to want.