GST to IST Time Converter
IST is 1 hour and 30 minutes ahead of GST. GST is UTC+4:00, and IST is UTC+5:30.
Best Time to Call Between GST and IST
Both zones are inside normal business hours between 9:00 AM and 4:00 PM GST — that's 10:30 AM to 5:30 PM IST. That's a 7-hour window.
both at work GST only IST only neither — hours along the strip are GST.
Common Times Converted
GST on the left, IST on the right.
GST to IST: Full 24-Hour Conversion Table
Shaded rows are working hours; the darker shade marks the hours when both zones are at work.
| GST | IST | Working hours |
|---|---|---|
| 12:00 AM | 1:30 AM | — |
| 1:00 AM | 2:30 AM | — |
| 2:00 AM | 3:30 AM | — |
| 3:00 AM | 4:30 AM | — |
| 4:00 AM | 5:30 AM | — |
| 5:00 AM | 6:30 AM | — |
| 6:00 AM | 7:30 AM | — |
| 7:00 AM | 8:30 AM | — |
| 8:00 AM | 9:30 AM | IST only |
| 9:00 AM | 10:30 AM | Both zones |
| 10:00 AM | 11:30 AM | Both zones |
| 11:00 AM | 12:30 PM | Both zones |
| 12:00 PM | 1:30 PM | Both zones |
| 1:00 PM | 2:30 PM | Both zones |
| 2:00 PM | 3:30 PM | Both zones |
| 3:00 PM | 4:30 PM | Both zones |
| 4:00 PM | 5:30 PM | GST only |
| 5:00 PM | 6:30 PM | — |
| 6:00 PM | 7:30 PM | — |
| 7:00 PM | 8:30 PM | — |
| 8:00 PM | 9:30 PM | — |
| 9:00 PM | 10:30 PM | — |
| 10:00 PM | 11:30 PM | — |
| 11:00 PM | 12:30 AM next day | — |
What GST and IST Actually Are
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.
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.
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 GST
Cities on IST
Frequently Asked Questions
What is the time difference between GST and IST?
IST is 1 hour and 30 minutes ahead of GST.
What is 9:00 AM GST in IST?
9:00 AM GST is 10:30 AM IST.
What are the best hours to schedule a call between GST and IST?
Between 9:00 AM and 4:00 PM GST, which is 10:30 AM to 5:30 PM IST. Both sides are inside normal business hours through that window.
Does the difference between GST and IST change during the year?
No. Neither region changes its clocks, so this gap is fixed all year round.
Does GST always mean Gulf Standard Time?
GST also refers to South Georgia Time (UTC-2), which you are very unlikely to want.
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.