IST Time Converter

The two cases, verified

Both cases below were checked against the browser's own time-zone data (Intl, Asia/Kolkata) before publication, not copied from a table. Winter: noon on 15 January 2027 in India is 12:00 IST, which is 06:30 UTC, 01:30 EST (New York), 00:30 CST (Chicago), 23:30 MST on 14 January (Denver), 22:30 PST on 14 January (Los Angeles), and 20:30 HST on 14 January (Honolulu). Summer: noon on 15 July 2027 in India is 12:00 IST, which is again 06:30 UTC — India never moves its clocks — but 02:30 EDT (New York), 01:30 CDT (Chicago), 00:30 MDT (Denver), 23:30 PDT on 14 July (Los Angeles), and 20:30 HST on 14 July (Honolulu). The UTC time never changes with the season; only the American labels move, because America springs forward and India does not.

What IST is, and why the half hour matters

IST (India Standard Time) is the single time zone for the whole of India, from Gujarat to Assam, set at UTC+5:30 — five and a half hours ahead of UTC. It is one of only a few half-hour offsets in the world, which is exactly why it trips people up: most converters and mental arithmetic default to whole hours, and a whole-hour guess is always thirty minutes wrong for India. The offset is fixed by law and has no daylight-saving variant, so an IST time in January and the same IST time in July convert to the same UTC time. That stability is a gift for scheduling — once you know a regular call is 06:30 UTC, it stays 06:30 UTC all year — but it also means the American side of the call drifts by an hour when the US changes its clocks.

India time vs IST naming, and the Irish IST trap

People say "India time" and "IST" for the same thing, and both are fine for the Asia/Kolkata zone — but the letters IST are shared. IST also stands for Irish Standard Time, the summer clock of Ireland (Europe/Dublin), which is UTC+1 in summer and does not exist in winter, when Ireland is on GMT. An invitation that says only "IST" without a place is therefore ambiguous: India at UTC+5:30 all year, or Ireland at UTC+1 in summer only. If a meeting invite says IST and the organiser is in Dublin, it is Irish time; if the organiser is in Mumbai, Delhi, or Bengaluru, it is India time. When you write an invite yourself, write "IST (India, UTC+5:30)" or "IST (Ireland)" and the ambiguity disappears. This page converts India time only.

The date flip: IST noon is America's previous evening

Because India is ten and a half hours ahead of New York in winter and nine and a half in summer, an Indian daytime hour is an American night-time hour — and often on the previous calendar day. Noon IST on 15 January is 01:30 the same morning in New York but 22:30 the previous evening in Los Angeles, and a 09:00 IST morning call is 23:30 the previous evening in New York. The most common India–US scheduling mistake is not the hour but the date: someone books "Tuesday" in India and the American colleague turns up on what is, for them, Monday night. The converter shows the date alongside every zone for exactly this reason. For regular calls, late evening in India is morning in America, and morning in India is late evening the day before in America — there is no overlap that is daytime in both.

Output · formula · meaning

Who uses this

• The remote worker joining an India call: enters the Indian meeting time and reads off their own US zone — and, crucially, the right date — without doing half-hour arithmetic in their head.
• The manager scheduling across continents: checks a regular IST slot in both January and July and learns the American side moves an hour while the Indian side never does.
• The traveller flying to Delhi or Mumbai: converts an arrival time before booking a connection, and avoids the classic thirty-minute whole-hour error.
• The student citing an Indian timestamp: converts an IST time to UTC for a paper, and uses the cite box below to reference this page properly.

Accuracy & limitations

Conversions use the browser's Intl time-zone database for Asia/Kolkata and the US zones, which is the same data operating systems use, so results track official rules. India has used a single zone at UTC+5:30 since independence, with no daylight saving at any point, so historical conversions within the database's range are stable; times before modern standardisation and far-future rule changes are outside its guarantees. This page converts India Standard Time only — it does not convert Irish Standard Time, which shares the letters IST but is a different zone (Europe/Dublin, UTC+1 in summer). Error policy: an empty or malformed date or time is reported as an error rather than converted.