How the IST converter handles a zone that never moves
India Standard Time stays at UTC+5:30 year-round. India does not observe daylight saving time, and it has not done so at the national level since the 1962 Sino-Indian war. The converter only needs to shift your local time by the correct offset, but that offset changes twice a year for most of the world.
The converter uses the IANA time zone database (Asia/Kolkata for India, Asia/Colombo for Sri Lanka) and applies the correct UTC offset for your target zone on the date you select. For example:
- 15 January 2026: New York is 10.5 hours behind IST.
- 15 July 2026: New York is 9.5 hours behind IST.
The difference is exactly one hour: New York switches to daylight time in March and back in November. The converter handles that automatically.
Why does the IST time converter need the date?
IST is one of a handful of time zones worldwide that uses a 30-minute offset from UTC. Others include Nepal (UTC+5:45), Iran (UTC+3:30), and parts of Australia (ACST at UTC+9:30). This is not a quirk, it was a deliberate choice in 1906, based on the 82.5°E meridian passing through Mirzapur.
The practical effect: mental math fails. Most people round to full hours and end up 30 minutes early or late for a meeting. If you manually calculate "New York is 10 hours behind India", you will be wrong by 30 minutes in January and 30 minutes the other way in July.
The converter eliminates that error. Always use it when scheduling across IST.
Which IST conversion do I need for a business call?
Business calls with the US
| US zone | Winter offset (Jan) | Summer offset (Jul) |
|---|---|---|
| Eastern (New York) | IST − 10.5 hours | IST − 9.5 hours |
| Central (Chicago) | IST − 11.5 hours | IST − 10.5 hours |
| Pacific (Los Angeles) | IST − 13.5 hours | IST − 12.5 hours |
Best overlap for calls: 07:00-09:30 EST (17:30-20:00 IST winter) or 19:00-21:00 EST (05:30-07:30 IST next day summer).
Europe and the Middle East
| City | Winter offset (Jan) | Summer offset (Jul) |
|---|---|---|
| London | IST − 5.5 hours | IST − 4.5 hours |
| Paris | IST − 4.5 hours | IST − 3.5 hours |
| Dubai | IST − 1.5 hours | IST − 1.5 hours |
Dubai never changes: no DST. London and Paris shift by one hour in March and October.
Asia-Pacific
| City | Offset (fixed) |
|---|---|
| Singapore | IST + 2.5 hours |
| Tokyo | IST + 3.5 hours |
| Sydney (winter) | IST + 5.5 hours |
| Sydney (summer) | IST + 4.5 hours |
Sydney observes DST in its summer (October to March), so the offset narrows by one hour during that period.
IST to major time zones at a glance
The table below shows the difference from IST for 15 January 2026 and 15 July 2026. Positive numbers mean the zone is ahead of IST; negative means behind.
| Zone | 15 January 2026 | 15 July 2026 |
|---|---|---|
| New York | −10.5 h | −9.5 h |
| Chicago | −11.5 h | −10.5 h |
| Los Angeles | −13.5 h | −12.5 h |
| London | −5.5 h | −4.5 h |
| Paris | −4.5 h | −3.5 h |
| Dubai | −1.5 h | −1.5 h |
| Johannesburg | −3.5 h | −3.5 h |
| São Paulo | −8.5 h | −8.5 h |
| Singapore | +2.5 h | +2.5 h |
| Tokyo | +3.5 h | +3.5 h |
| Sydney | +5.5 h | +4.5 h |
Zones without DST (Dubai, Johannesburg, Singapore, Tokyo) stay constant year-round. All others shift when their clocks change.