IST stays put. US zones move twice a year
India runs on a single fixed offset: UTC+5:30, all year. No clock changes, no summer time, no exceptions. The United States shifts its clocks forward in spring and back in autumn. Every US time zone therefore has two different gaps from IST, depending on the date.
From the second Sunday of March to the first Sunday of November, US clocks are on daylight time (EDT, CDT, MDT, PDT). The rest of the year they run on standard time (EST, CST, MST, PST).
IST to Eastern Time: 10.5 or 9.5 hours ahead
Eastern Time covers New York, Washington DC, Boston, Atlanta, and Miami.
| Period | US time zone | Gap from IST |
|---|---|---|
| Early November to mid-March | Eastern Standard Time (EST, UTC-5) | IST is 10.5 hours ahead |
| Mid-March to early November | Eastern Daylight Time (EDT, UTC-4) | IST is 9.5 hours ahead |
Example: 12:00 noon IST is 01:30 EST (previous night) or 02:30 EDT (previous night).
IST to Central Time: 11.5 or 10.5 hours ahead
Central Time covers Chicago, Dallas, and Houston.
| Period | US time zone | Gap from IST |
|---|---|---|
| Early November to mid-March | Central Standard Time (CST, UTC-6) | IST is 11.5 hours ahead |
| Mid-March to early November | Central Daylight Time (CDT, UTC-5) | IST is 10.5 hours ahead |
Example: 12:00 noon IST is 00:30 CST or 01:30 CDT.
IST to Mountain Time: 12.5 or 11.5 hours ahead
Mountain Time covers Denver and Salt Lake City. Phoenix stays on Mountain Standard Time all year.
| Period | US time zone | Gap from IST |
|---|---|---|
| Early November to mid-March | Mountain Standard Time (MST, UTC-7) | IST is 12.5 hours ahead |
| Mid-March to early November | Mountain Daylight Time (MDT, UTC-6) | IST is 11.5 hours ahead |
Example: 12:00 noon IST is 23:30 MST (previous day) or 00:30 MDT.
IST to Pacific Time: 13.5 or 12.5 hours ahead
Pacific Time covers Los Angeles, San Francisco, and Seattle.
| Period | US time zone | Gap from IST |
|---|---|---|
| Early November to mid-March | Pacific Standard Time (PST, UTC-8) | IST is 13.5 hours ahead |
| Mid-March to early November | Pacific Daylight Time (PDT, UTC-7) | IST is 12.5 hours ahead |
Example: 12:00 noon IST is 22:30 PST (previous day) or 23:30 PDT (previous day).
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US Eastern (EST/EDT): - Standard time (winter): 07:00-09:00 EST = 17:30-19:30 IST. Evening in India, early morning on the US East Coast. - Daylight time (summer): 19:00-21:00 EDT = 05:30-07:30 IST next day. Early morning in India, late afternoon on the US East Coast.
US Pacific (PST/PDT): - Standard time (winter): 07:00-09:00 PST = 20:30-22:30 IST. Late evening in India, early morning on the West Coast. - Daylight time (summer): 19:00-21:00 PDT = 07:30-09:30 IST next day. Morning in India, late afternoon on the West Coast.
The most reliable overlap is US morning (07:00-09:00 local) paired with India evening (17:30-22:30 IST, depending on the US zone and whether DST is in effect).
How the US clock change hits the gap
The US springs forward on the second Sunday of March and falls back on the first Sunday of November.
In 2027, US DST starts on 14 March and ends on 7 November.
On the spring change, clocks jump from 02:00 to 03:00 local time. The gap between IST and that US zone drops by one hour overnight. In autumn, clocks fall back from 02:00 to 01:00, and the gap widens by one hour.
IT and BPO shifts built around US hours (often 20:00-05:00 IST) shift by one hour relative to the US clock twice a year. Operations teams adjust start times to match.
Quick reference: IST to four US zones
| US time zone | Standard time (Nov, Mar) | Daylight time (Mar, Nov) |
|---|---|---|
| Eastern | IST +10.5 h | IST +9.5 h |
| Central | IST +11.5 h | IST +10.5 h |
| Mountain | IST +12.5 h | IST +11.5 h |
| Pacific | IST +13.5 h | IST +12.5 h |