What this does
Enter a time in India Standard Time and read it in US Eastern Time. India is well ahead: 9 hours 30 minutes ahead of EST in the US winter, and 10 hours 30 minutes ahead in the US summer. The half-hour is real — IST is one of the world's offset-by-30-minutes zones (UTC+5:30).
Why does the gap change between 9.5 and 10.5 hours?
India does not observe daylight saving — IST is UTC+5:30 all year. The US does, so when the Eastern clock springs forward in summer (EDT, UTC−4), the distance to India shrinks by an hour to 9.5 hours; in winter (EST, UTC−5) it's 10.5 hours. All the movement is on the US side. The converter above applies the correct gap for whatever date you enter.
Quick IST → EST reference (US winter, 10.5h gap)
- 9:00 AM IST → 10:30 PM EST (previous day)
- 1:00 PM IST → 2:30 AM EST
- 6:30 PM IST → 8:00 AM EST
- 9:30 PM IST → 11:00 AM EST
In US summer, the Eastern times above shift an hour later.
When can India and the US East Coast actually meet?
The workday overlap is narrow and lands in India's evening. A slot around 6:30–8:30 PM IST is roughly 8:00–10:00 AM Eastern — early for the US, after-hours for India, but it's the practical window most India–US East Coast teams settle on. Earlier IST times fall in the middle of the US night.
Does this work for IST to other US zones?
This page is Eastern-specific. For Central, Mountain, or Pacific, the timezone tool lets you place Asia/Kolkata next to any US zone. Most India-based teams working with US clients use Eastern as the reference, which is why it has its own page here.
Related
See UTC to IST for converting server time to India, or UTC to EST for the US side.