Convert IST to CST
CST = IST −11 h 30 min
CST is 11 hours 30 minutes behind IST. IST is always UTC+5:30 and CST is always UTC−6, so this gap is the same on every date.
IST · India Standard Time · UTC+5:30
5:44PM
Tuesday, November 3, 2026
CST · Central Standard Time · UTC−6
6:14AM
Tuesday, November 3, 2026
Chicago is on CST (UTC−6) right now.
- Next clock change: March 14, 2027. Chicago moves to CDT (UTC−5), so Chicago is then 10 hours 30 minutes behind India.
- Next clock change: November 7, 2027. Chicago moves to CST (UTC−6), so Chicago is then 11 hours 30 minutes behind India.
IST to CST for every hour
Each CST column holds for part of the year (dates in the header for 2027). The first uses the fixed offsets (IST UTC+5:30, CST UTC−6); the others give local clock time when daylight saving time changes the gap. Until 11:30 AM IST, CST is still on the previous calendar day.
| IST | CST −11 h 30 minfixed offsets | CST −10 h 30 minMar 14 – Nov 7 | 24-hour |
|---|---|---|---|
| 12:00 AM | 12:30 PM −1 day | 1:30 PM −1 day | 00:00 → 12:30 |
| 1:00 AM | 1:30 PM −1 day | 2:30 PM −1 day | 01:00 → 13:30 |
| 2:00 AM | 2:30 PM −1 day | 3:30 PM −1 day | 02:00 → 14:30 |
| 3:00 AM | 3:30 PM −1 day | 4:30 PM −1 day | 03:00 → 15:30 |
| 4:00 AM | 4:30 PM −1 day | 5:30 PM −1 day | 04:00 → 16:30 |
| 5:00 AM | 5:30 PM −1 day | 6:30 PM −1 day | 05:00 → 17:30 |
| 6:00 AM | 6:30 PM −1 day | 7:30 PM −1 day | 06:00 → 18:30 |
| 7:00 AM | 7:30 PM −1 day | 8:30 PM −1 day | 07:00 → 19:30 |
| 8:00 AM | 8:30 PM −1 day | 9:30 PM −1 day | 08:00 → 20:30 |
| 9:00 AM | 9:30 PM −1 day | 10:30 PM −1 day | 09:00 → 21:30 |
| 10:00 AM | 10:30 PM −1 day | 11:30 PM −1 day | 10:00 → 22:30 |
| 11:00 AM | 11:30 PM −1 day | 12:30 AM | 11:00 → 23:30 |
| 12:00 PM | 12:30 AM | 1:30 AM | 12:00 → 00:30 |
| 1:00 PM | 1:30 AM | 2:30 AM | 13:00 → 01:30 |
| 2:00 PM | 2:30 AM | 3:30 AM | 14:00 → 02:30 |
| 3:00 PM | 3:30 AM | 4:30 AM | 15:00 → 03:30 |
| 4:00 PM | 4:30 AM | 5:30 AM | 16:00 → 04:30 |
| 5:00 PM | 5:30 AM | 6:30 AM | 17:00 → 05:30 |
| 6:00 PM | 6:30 AM | 7:30 AM | 18:00 → 06:30 |
| 7:00 PM | 7:30 AM | 8:30 AM | 19:00 → 07:30 |
| 8:00 PM | 8:30 AM | 9:30 AM | 20:00 → 08:30 |
| 9:00 PM | 9:30 AM | 10:30 AM | 21:00 → 09:30 |
| 10:00 PM | 10:30 AM | 11:30 AM | 22:00 → 10:30 |
| 11:00 PM | 11:30 AM | 12:30 PM | 23:00 → 11:30 |
Bold rows fall inside office hours (9:00 to 17:00) on both sides. The dot marks the current IST hour.
The IST times people look up most
| IST | CST −11 h 30 min | CST −10 h 30 min |
|---|---|---|
| 7:30 PM | 8:00 AM | 9:00 AM |
| 5:15 AM | 5:45 PM −1 day | 6:45 PM −1 day |
| 8:15 PM | 8:45 AM | 9:45 AM |
| 9:41 AM | 10:11 PM −1 day | 11:11 PM −1 day |
| 9:41 PM | 10:11 AM | 11:11 AM |
| 9:30 AM | 10:00 PM −1 day | 11:00 PM −1 day |
| 1:30 AM | 2:00 PM −1 day | 3:00 PM −1 day |
Does the difference change during the year?
As written, no: IST is always UTC+5:30 and CST is always UTC−6, so the gap is 11 hours 30 minutes on every date. But Chicago uses CST only in winter, and people often keep writing “CST” when they mean the local time. Between the local clocks of India and Chicago, the gap is 11 hours 30 minutes or 10 hours 30 minutes:
| From | What changes | India | Chicago | CST vs IST |
|---|---|---|---|---|
| January 1 | Start of the year | IST (UTC+5:30) | CST (UTC−6) | −11 h 30 min |
| March 8 | Chicago moves to CDT (UTC−5) | IST (UTC+5:30) | CDT (UTC−5) | −10 h 30 min |
| November 1 | Chicago moves to CST (UTC−6) | IST (UTC+5:30) | CST (UTC−6) | −11 h 30 min |
| From | What changes | India | Chicago | CST vs IST |
|---|---|---|---|---|
| January 1 | Start of the year | IST (UTC+5:30) | CST (UTC−6) | −11 h 30 min |
| March 14 | Chicago moves to CDT (UTC−5) | IST (UTC+5:30) | CDT (UTC−5) | −10 h 30 min |
| November 7 | Chicago moves to CST (UTC−6) | IST (UTC+5:30) | CST (UTC−6) | −11 h 30 min |
Converting IST to CST by hand
With the fixed offsets, take away 11 hours 30 minutes: 3:30 PM IST is 4:00 AM CST. In your head it is easier to swap AM and PM, then add 30 minutes: 3:30 PM, 3:30 AM, 4:00 AM.
With the −10 h 30 min gap (Mar 14 – Nov 7), take away 10 hours 30 minutes: 3:30 PM IST is 5:00 AM CST. In your head it is easier to swap AM and PM, then add 1 hour 30 minutes: 3:30 PM, 3:30 AM, 5:00 AM.
Going back from CST to IST, do the opposite: the CST to IST page has its own table.
Where the IST and CST working days overlap
IST to CST (−11 h 30 min): Two 9:00–17:00 days do not overlap at all. To meet between 7:00 AM and 9:00 PM on both sides, start at 7:00 AM to 8:00 AM IST (7:30 PM to 8:30 PM CST), or 7:00 PM to 9:00 PM IST (7:30 AM to 9:30 AM CST).
−10 h 30 min (between Mar 14 and Nov 7, 2027): Two 9:00–17:00 days do not overlap at all. To meet between 7:00 AM and 9:00 PM on both sides, start at 7:00 AM IST (8:30 PM CST), or 6:00 PM to 9:00 PM IST (7:30 AM to 10:30 AM CST).
A meeting fixed in one city’s calendar moves by an hour for the other when the gap changes. Calendar apps handle this when the event is saved in a named zone (for example Asia/Kolkata) rather than as a fixed offset.
What IST and CST mean
India Standard Time
IST here is India Standard Time, UTC+5:30, used in all of India all year: no daylight saving time and a single zone for the whole country.
IST can also mean Israel Standard Time (UTC+2, Israel) or Irish Standard Time (UTC+1, Ireland, in summer). This page uses India Standard Time, the meaning people searching for this conversion have in mind. For another one, type the city into the time zone converter.
Central Standard Time
CST here is North American Central Standard Time, UTC−6: winter time in Chicago, Houston and Dallas, and all-year time in Mexico City, most of Central America and Saskatchewan. Since 2026 Alberta and the Northwest Territories also stay on UTC−6 all year.
CST can also mean China Standard Time (UTC+8, China) or Cuba Standard Time (UTC−5, Cuba). This page uses Central Standard Time, the meaning people searching for this conversion have in mind. For another one, type the city into the time zone converter.