IST to EST: the conversion that moves twice a year
India is 9:30 or 10:30 ahead of New York depending on the date — and India never changes its clocks. The whole shift comes from the American side.
The short answer
India is 10:30 hours ahead of New York in winter, and 9:30 hours ahead in summer.
India Standard Time is UTC+5:30 and never changes. New York moves between UTC−5 and UTC−4. So the gap is 10:30 hours from November to March and 9:30 hours from March to November — and India has nothing to do with the change.
The half hour is the point
India sits at UTC+5:30. Not +5, not +6. That half hour is not a rounding error and not a bug in your calendar — it is the actual legal time of the country, set on a meridian near Mirzapur.
Any tool that works in whole hours gets India wrong. So does any mental shortcut that rounds. This is the conversion that separates a converter which reads the IANA database from one that guesses.
Both answers, and when each applies
| New York | India | Gap | |
|---|---|---|---|
| Nov – Mar | EST · UTC−5 | IST · UTC+5:30 | 10 hours 30 minutes |
| Mar – Nov | EDT · UTC−4 | IST · UTC+5:30 | 9 hours 30 minutes |
Worked both ways, in the summer case (9:30):
- 9:00 New York → 18:30 India, same day
- 12:00 New York → 21:30 India, same day
- 17:00 New York → 02:30 India, next day
- 09:00 India → 23:30 New York, previous day
In winter, add an hour to every India figure above.
Why the gap moves when India doesn't
India has not observed daylight saving time since the 1940s. Its offset is constant, every day of the year.
The United States does observe it. When New York springs forward in March, it moves from UTC−5 to UTC−4 — an hour closer to India. The distance between the two countries shrinks by an hour without a single clock in India being touched.
This produces a genuinely counter-intuitive situation: colleagues in Bengaluru experience their call with New York moving by an hour, twice a year, for reasons entirely outside their country.
The three weeks nobody warns you about
The US changes in March and November. The European Union changes on different weekends. If your call includes London and Mumbai and New York, there are short windows each year when only one of the three has shifted, and every recurring invite in the chain is wrong by an hour.
The fix is the same as always: schedule against cities, not offsets, and let the time zone database resolve the date.
What this means for scheduling
The overlap between US Eastern working hours and Indian working hours is narrow, and it sits at the edges of both days. With an 08:00–22:00 waking window on both sides, the shared hours land in the early US morning and the late Indian evening — which is why teams split across these two zones tend to converge on a single fixed handover slot rather than trying to find a new time each week.
That is a scheduling decision, not an arithmetic one. There is a scenario page about what happens when nobody checks the overlap before signing the offer.
Writing it down safely
- Best: “6pm Mumbai / 8:30am New York.”
- Acceptable: “IST” — it is unambiguous for India and never changes.
- Risky: “EST” for the American side. In summer that is wrong; see EST vs EDT.
One caution: IST is itself ambiguous internationally. It is also used for Irish Standard Time and Israel Standard Time. Within an India context it is clear; in a mixed thread, write the city.
Related: EST vs EDT · UTC to EST
Timezone: World Clock Widget
A world clock, converter and live day/night map for iPhone — 325 cities, offline, no account.
Figures on this page are computed from the IANA time zone database. Last generated 2026-08-18.