How many hours is IST ahead of MST?
As abbreviations, MST is always 12.5 hours behind of IST: IST is UTC+5:30 and MST is UTC−7. To convert, subtract 12.5 hours.
Check which label you actually need: MST (Mountain Time is on MDT today). A time written with an abbreviation that is not in use is usually meant as the local time, so convert between the places instead: right now MST is 11.5 hours behind of IST.
When the IST to MST time difference changes
For most of the year MST is 11.5 hours behind of IST. From 1 November to 31 December 2026, MST is 12.5 hours behind of IST instead, because the two places change their clocks on different dates. Meetings booked by the usual gap land an hour off in those weeks.
| Dates | MST vs IST | Length |
|---|---|---|
| 8 March 2026 to 31 October 2026 | 11.5 hours behind | 238 days |
| 1 November 2026 to 31 December 2026 | 12.5 hours behind | 61 days |
| 1 January 2027 to 13 March 2027 | 12.5 hours behind | 72 days |
| 14 March 2027 to 6 November 2027 | 11.5 hours behind | 238 days |
| 7 November 2027 to 31 December 2027 | 12.5 hours behind | 55 days |
When IST and MST are both at work
- When MST is 11.5 hours behind of IST: no shared 09:00 to 17:00 hours; try 19:00 in IST (07:30 in MST).
- When MST is 12.5 hours behind of IST: no shared 09:00 to 17:00 hours; try 20:00 in IST (07:30 in MST).