IST to MST Time Zone Converter
India Standard Time to US Mountain Time lines up India's clock with Denver, Salt Lake City, and Phoenix — and it drops you onto the previous day. Mountain is 12 hours 30 minutes behind India in winter and 11 hours 30 minutes behind in summer, because most of the US Mountain zone shifts to daylight time while India never changes. Morning in India is the night before in the Rockies.
Enter a date and time to convert.
Daylight saving is applied automatically for the date you pick. Labels like PST/EST name the zone (Pacific/Eastern); the real abbreviation shifts to PDT/EDT during daylight saving, and gmt here means London (GMT in winter, BST in summer) while utc stays fixed.
The time difference
US Mountain Time is 12 hours 30 minutes behind India in winter and 11 hours 30 minutes behind in summer. India (Kolkata, Mumbai, Delhi, Bangalore) never moves from UTC+5:30, but the Mountain zone springs forward on Mar 8, 2026 and falls back on Nov 1, 2026. Since only the US side shifts, the gap closes by an hour over the summer.
A worked example
Take 9:00 AM in India. On Jan 15, 2026 that is 8:30 PM the night before — Wed, Jan 14 — in Denver. On Jul 15, 2026 it's 9:30 PM on Tue, Jul 14. Mind the day: an India morning lands on the previous calendar date in the Rockies. That day change is the classic slip when booking an India-US call, so fix the date, not just the clock.
Daylight saving & the abbreviation caveat
"MST" is the winter name. From spring to fall the Mountain zone runs on MDT (Mountain Daylight Time), an hour ahead, and locals just say "Mountain" or "MT" year-round. India never observes daylight saving — it holds at UTC+5:30 always — so the shifting is all on the US side. The converter picks the right Mountain offset for your exact date, which is why the summer result differs by an hour.
When you'll use it
Scheduling a call between an India team and a Denver or Salt Lake City office, timing a US live event, joining a Mountain-zone market open, or setting overlap hours for remote work — always checking which calendar day the US side lands on.
Frequently asked questions
How far behind IST is Mountain Time?
12 hours 30 minutes in winter (MST) and 11 hours 30 minutes in summer (MDT). India stays fixed while the Mountain zone springs forward, so the gap narrows by an hour from spring to fall.
Why does a morning in India land on the day before in Denver?
With a 12-plus-hour gap, subtracting from an India morning carries you past midnight into the prior evening in the Mountain zone. It trips up India-US scheduling, so always confirm the date, not just the time.
Is MST the same as Denver time?
In winter, yes. From spring to fall Denver runs on MDT (Mountain Daylight Time), one hour ahead; locals just say 'Mountain' or 'MT' either way. (Arizona is the exception — it stays on MST all year.)