India Standard Time Converter — IST to EST, GMT, PST and More
Updated: May 2026
India Standard Time (IST) is UTC+5:30 — one of only a handful of time zones in the world that uses a half-hour increment. India does not observe Daylight Saving Time, making IST a stable, predictable reference point: the offset from UTC never changes. However, countries like the US, UK, and much of Europe do change their clocks seasonally, which means IST's offset relative to those zones varies throughout the year.
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IST offsets from major world cities
| City / Zone | IST offset (winter) | IST offset (summer) |
|---|---|---|
| New York (EST/EDT) | IST = EST + 10h30m | IST = EDT + 9h30m |
| Los Angeles (PST/PDT) | IST = PST + 13h30m | IST = PDT + 12h30m |
| London (GMT/BST) | IST = GMT + 5h30m | IST = BST + 4h30m |
| Paris / Berlin (CET/CEST) | IST = CET + 4h30m | IST = CEST + 3h30m |
| Dubai (GST, UTC+4) | IST = GST + 1h30m (no DST in Dubai) | |
| Singapore (SGT, UTC+8) | IST = SGT - 2h30m (no DST in Singapore) | |
| Tokyo (JST, UTC+9) | IST = JST - 3h30m (no DST in Japan) | |
| Sydney (AEST/AEDT) | IST = AEST - 4h30m | IST = AEDT - 5h30m |
IST's offset from any DST-observing country changes twice a year — not because India changes, but because the other country does. Always verify the current offset when scheduling across India and a DST-observing zone near a transition date.
IST to EST working hours overlap
Scheduling between India and the US East Coast is one of the most common cross-continental challenges in global IT and outsourcing. With a 10.5-hour difference in winter and 9.5 hours in summer, there is very little natural overlap within standard 9–5 business hours.
- Morning IST / night EST: 9:00 AM IST = 10:30 PM EST the previous day. Not workable for US calls.
- Afternoon IST / early morning EST: 1:00 PM IST = 2:30 AM EST. Still impractical.
- Evening IST / morning EST (winter): 8:00 PM IST = 9:30 AM EST. This is the prime window — end of day India, start of day New York.
- Evening IST / morning EDT (summer): 7:00 PM IST = 9:30 AM EDT. Shifts one hour earlier for India during US DST.
- Late evening IST / afternoon EST: 10:30 PM IST = 12:00 PM EST. Late for India but workable if the Indian team works flexible hours.
In practice, India-US remote teams typically schedule daily standups at 8:00–9:30 PM IST / 9:30–11:00 AM EST (winter) or 7:00–8:30 PM IST / 9:30–11:00 AM EDT (summer). The India side usually works a split shift or extended evening to accommodate this overlap.
IST to GMT/BST — India and the UK
London and India have a closer and less disruptive overlap than India and the US. The gap is 5.5 hours in winter (GMT) and 4.5 hours in summer (BST). Standard Indian business hours (9 AM–6 PM IST) overlap with UK afternoon hours.
- 9:00 AM IST = 3:30 AM GMT (5:30 before UK workday starts — no overlap)
- 1:30 PM IST = 8:00 AM GMT (UK just opening)
- 6:00 PM IST = 12:30 PM GMT / 1:30 PM BST (peak UK afternoon — best window)
- Overlap window: 1:30 PM–6:00 PM IST / 8:00 AM–12:30 PM GMT. Nearly a full morning for the UK within Indian working hours.
The India-UK corridor has much more natural overlap than India-US. Morning UK calls are afternoon India calls, making it relatively easy to find slots that work for both parties without anyone working outside standard hours.
Why India chose UTC+5:30
India spans approximately 30 degrees of longitude, from roughly 68°E (western Gujarat) to 97°E (eastern Arunachal Pradesh). At 1 hour per 15° of longitude, this would naturally suggest a 2-hour span of local solar time across the country.
At independence in 1947, the government chose a single time zone as a practical and symbolic act of national unity, rather than splitting the country into multiple zones as the British colonial administration had done. UTC+5:30 was selected as the nearest round-or-half-hour increment to the geographic midpoint (roughly 82°E, Allahabad). The Allahabad observatory at 82.5°E is the reference point for IST's legal definition.
The half-hour increment means India is always half-aligned to neighboring zones. Pakistan uses UTC+5, Bangladesh uses UTC+6, and Sri Lanka shares IST. Nepal went even further — UTC+5:45 — specifically to remain distinct from India.
Frequently asked questions
What is IST time zone?
IST stands for India Standard Time. It is UTC+5:30 (5 hours and 30 minutes ahead of UTC). It is used across all of India and is the same as Sri Lanka Standard Time. India does not observe DST — the offset is fixed year-round.
What is the time difference between IST and EST?
IST is 10 hours and 30 minutes ahead of EST in winter (UTC-5). During US DST (summer), IST is 9 hours and 30 minutes ahead of EDT (UTC-4). India does not change its clocks, so the gap shifts when the US adjusts for DST.
Why does India use a half-hour offset?
India chose UTC+5:30 at independence in 1947 as a compromise between its eastern and western geographic extents. The reference meridian at 82.5°E (Allahabad) corresponds to UTC+5:30 solar time. A whole-hour offset in either direction would have been too early or too late for half the country.
What is the best time to schedule a meeting between India and New York?
The best window is 8:00–9:30 PM IST / 9:30–11:00 AM EST (winter) or 7:00–8:30 PM IST / 9:30–11:00 AM EDT (summer). This gives India late-evening hours and New York a morning slot. The India side typically works an extended day for US calls.
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