IST can mean 3 different things depending on where you are: India Standard Time (UTC+5:30); Irish Standard Time (UTC+1); Israel Standard Time (UTC+2). Each is explained below.
IST stands for India Standard Time and is UTC+5:30, which is 5 hours 30 minutes ahead of UTC.
The places that use IST do not change their clocks for daylight saving time, so the offset stays UTC+5:30 all year.
Cities that use IST: Bangalore, Mumbai, New Delhi, Chennai, Kolkata, Hyderabad, Pune, Jaipur, Surat, Kanpur, Nagpur, Lucknow, Bhopal, Coimbatore and 18 more.
| When it is… | 9:00 AM IST | 12:00 PM IST | 5:00 PM IST |
|---|---|---|---|
| UTC | 3:30 AM | 6:30 AM | 11:30 AM |
| PST (Pacific) | 7:30 PM (-1 day) | 10:30 PM (-1 day) | 3:30 AM |
| MST (Mountain) | 8:30 PM (-1 day) | 11:30 PM (-1 day) | 4:30 AM |
| CST (Central US) | 9:30 PM (-1 day) | 12:30 AM | 5:30 AM |
| EST (Eastern) | 10:30 PM (-1 day) | 1:30 AM | 6:30 AM |
| CET (Central Europe) | 4:30 AM | 7:30 AM | 12:30 PM |
| EET (Eastern Europe) | 5:30 AM | 8:30 AM | 1:30 PM |
| JST (Japan) | 12:30 PM | 3:30 PM | 8:30 PM |
| AEST (Sydney) | 1:30 PM | 4:30 PM | 9:30 PM |
IST stands for Irish Standard Time and is UTC+1, which is 1 hour ahead of UTC.
The places that use IST also use GMT (UTC+0) for the rest of the year.
Cities that use IST: Dublin, Cork.
| When it is… | 9:00 AM IST | 12:00 PM IST | 5:00 PM IST |
|---|---|---|---|
| UTC | 8:00 AM | 11:00 AM | 4:00 PM |
| PST (Pacific) | 12:00 AM | 3:00 AM | 8:00 AM |
| MST (Mountain) | 1:00 AM | 4:00 AM | 9:00 AM |
| CST (Central US) | 2:00 AM | 5:00 AM | 10:00 AM |
| EST (Eastern) | 3:00 AM | 6:00 AM | 11:00 AM |
| EET (Eastern Europe) | 10:00 AM | 1:00 PM | 6:00 PM |
| IST (India) | 1:30 PM | 4:30 PM | 9:30 PM |
| JST (Japan) | 5:00 PM | 8:00 PM | 1:00 AM (+1 day) |
| AEST (Sydney) | 6:00 PM | 9:00 PM | 2:00 AM (+1 day) |
IST stands for Israel Standard Time and is UTC+2, which is 2 hours ahead of UTC.
The same places switch to IDT (UTC+3) while daylight saving time is in effect.
Cities that use IST: Jerusalem, Tel Aviv, Haifa.
| When it is… | 9:00 AM IST | 12:00 PM IST | 5:00 PM IST |
|---|---|---|---|
| UTC | 7:00 AM | 10:00 AM | 3:00 PM |
| PST (Pacific) | 11:00 PM (-1 day) | 2:00 AM | 7:00 AM |
| MST (Mountain) | 12:00 AM | 3:00 AM | 8:00 AM |
| CST (Central US) | 1:00 AM | 4:00 AM | 9:00 AM |
| EST (Eastern) | 2:00 AM | 5:00 AM | 10:00 AM |
| CET (Central Europe) | 8:00 AM | 11:00 AM | 4:00 PM |
| IST (India) | 12:30 PM | 3:30 PM | 8:30 PM |
| JST (Japan) | 4:00 PM | 7:00 PM | 12:00 AM (+1 day) |
| AEST (Sydney) | 5:00 PM | 8:00 PM | 1:00 AM (+1 day) |
IST can stand for India Standard Time; Irish Standard Time; Israel Standard Time.
India Standard Time is UTC+5:30. Irish Standard Time is UTC+1. Israel Standard Time is UTC+2.
It depends on context. Look at the place or the schedule the abbreviation comes from, or ask for the UTC offset to be written out, such as UTC+8 instead of CST.