IST stands for India Standard Time, the time zone used across all of India and Sri Lanka. It is UTC+5:30, five and a half hours ahead of Coordinated Universal Time. India does not observe daylight saving, so the offset stays fixed all year. The same abbreviation can also mean Israel Standard Time or Irish Standard Time.
IST is one of the cleanest time zones in the world to describe and one of the easiest to get wrong. A single offset covers an entire subcontinent, it never changes for daylight saving, and yet that half hour quietly breaks almost every mental conversion people attempt.
What does IST stand for?
In everyday use, IST means India Standard Time. It is the official civil time for the whole of India, from Mumbai to Kolkata, and is also used by Sri Lanka. Unlike countries that span several zones, India runs on one clock nationwide, so 3:00 PM in Delhi is 3:00 PM in Bangalore and 3:00 PM in Chennai.
What is the UTC offset for IST?
India Standard Time is UTC+5:30: five hours and thirty minutes ahead of Coordinated Universal Time. That extra half hour is the detail that catches people out, because most time zones sit on a whole hour. When it is 12:00 noon UTC, it is 5:30 PM in India.
| Property | Value |
|---|---|
| Abbreviation | IST |
| Full name | India Standard Time |
| UTC offset | UTC+5:30 |
| Daylight saving | Not observed |
| Used by | India, Sri Lanka |
| Offset hours ahead of UTC | 5.5 (fixed year-round) |
Does India observe daylight saving?
No. India does not observe daylight saving time, so IST stays on UTC+5:30 every day of the year. This makes India simpler than many partners: the offset to India only ever changes because the other region springs forward or falls back, never because India does. A city in the United States or Europe will swing by an hour twice a year while India sits perfectly still.
Why is IST half an hour off?
India stretches across a wide band of longitude, far enough that its eastern and western edges would naturally fall into different whole-hour zones. Rather than split the country, India settled on a single half-hour compromise that keeps everyone on one clock while keeping noon reasonably close to the midday sun. The result is tidy inside India and awkward everywhere else.
If you assume India is a whole number of hours away, you will be 30 minutes off every single time. A 9:00 AM call in New York is 6:30 PM in Mumbai, not 6:00 or 7:00. For the deeper reason these offsets exist, see why some time zones are 30 or 45 minutes off.
IST can mean other things too
The abbreviation IST is not unique to India. It is also used for Israel Standard Time (UTC+2) and Irish Standard Time (UTC+1, Ireland's summer time). If a calendar invite or flight itinerary just says "IST", check the location before you trust it, because the three meanings are hours apart. When in doubt, work from the city name and the actual offset rather than the three letters.
What IST means for scheduling
The practical takeaway is to never do round-number arithmetic when India is involved. Read each person's real local time instead, half hour and all. That is exactly what Atlas does: pin a colleague in India, see their live IST clock next to yours, and book the moment everyone is awake without touching a calculator. If you call India regularly, our guide to the best time to call India from the USA walks through the overlapping hours.
Frequently asked
What does IST stand for?
What is the UTC offset for India Standard Time?
Does India observe daylight saving time?
Why is India Standard Time half an hour off?
Stop doing timezone math
Atlas finds the time everyone's awake and adds it to your calendar in one tap.
One-time purchase, yours forever.