IST to EST time converter

How far apart are Kolkata and New York?

It depends on the date. New York is 9 hours 30 minutes behind Kolkata while Kolkata is on IST and New York on EDT. New York is 10 hours 30 minutes behind Kolkata while Kolkata is on IST and New York on EST. The exact dates for 2026 and 2027 are below, worked out from the same time zone database your browser uses — not remembered.

2026

2027

IST to EST hour table

Every hour of a Kolkata day, read across to New York — one column per gap, so pick the column for today's date from the table above. A row marked +1 day is already tomorrow there; −1 day is still yesterday.

Each column is one value of the gap; the clock names under it are the ones in force when that gap applies. For a half-hour time or a third city, use the timeline above: every clock moves to the instant you pick.

Working across Kolkata and New York

The IST to EST conversion is awkward for two separate reasons, and most people only know about one of them. The first is the half hour: India runs at UTC+5:30, so an even hour in New York is always a half hour in India. Nine in the morning in New York, in winter, is half past seven in the evening in Kolkata, Mumbai, Bengaluru and Delhi — every Indian city keeps the same clock, there is only one Indian time zone. The second reason is that India does not change its clocks and the United States does, so the distance between the two moves twice a year without anyone in India doing anything.

From early November to early March New York is on Eastern Standard Time, UTC−5, and the gap is ten and a half hours. From the second Sunday in March to the first Sunday in November it is on Eastern Daylight Time, UTC−4, and the gap shrinks to nine and a half. The exact dates for this year and next are computed above from your browser's own time zone database, not copied from a calendar. A recurring meeting fixed at a New York time will land half an hour to an hour later in India for eight months of the year and earlier for the other four — which is why a standing 9pm IST call becomes an 8pm one every March and nobody remembers agreeing to that.

The working-day overlap is thin but real. When it is 9am in New York it is already evening in India, and when India's day starts at 9am, New York is still asleep at half past ten the previous night. The window that works for both is roughly 8am to 11am Eastern, which is 5:30pm to 8:30pm in India during Eastern Daylight Time and 6:30pm to 9:30pm during Eastern Standard Time. Teams that run this pair well usually accept an early start on the American side or a late finish on the Indian one, and alternate which. The timeline above shows the daylight bands so you can see which side is being asked to work in the dark before you propose a time.

Two things people get wrong when they do this sum by hand. The first is the date: at 10pm in New York on a Friday it is already Saturday morning in India, so a deadline written as "end of day Friday, Eastern" is a Saturday-morning deadline for a colleague in Pune. The hour table marks the day change with a plus one for exactly this reason. The second is the abbreviation itself. IST is also Israel Standard Time (UTC+2) and Irish Standard Time (UTC+1); a calendar invite that just says IST is relying on context to mean India. This page and the tool above work in the unambiguous zone names Asia/Kolkata and America/New_York, and only use the letters because that is what people search for.

If what you have is a Unix timestamp rather than a clock time, decode it first in the epoch converter and then read it here — a timestamp has no time zone, and the conversion only starts once you know which wall clock it was written against.

Sources

The offsets, dates and hour tables above are computed when this page is built, from the time zone rules your browser itself ships. The rules come from:

• IANA Time Zone Database — the rules every browser ships
• NIST — Daylight Saving Time rules (United States)
• ECMA-402 — the Intl.DateTimeFormat standard these figures are computed with