IST: which one do you mean?
IST means 3 different things, and they are hours apart. If you received a timestamp labelled IST, the sender's location decides which of these applies, so pick it below.
India Standard Time · Asia
07:15:50
Sunday, 27 September 2026
- abbreviation denotes
- +05:30
- in force right now
- IST (UTC+05:30)
- use in code
- Asia/Kolkata
- also valid
- Asia/Colombo
- next clock change
- none, fixed offset
By far the most common meaning by search volume.
Irish Standard Time · Europe
02:45:50
Sunday, 27 September 2026
- abbreviation denotes
- +01:00
- in force right now
- IST (UTC+01:00) · DST
- use in code
- Europe/Dublin
- next clock change
- 25 Oct 2026 01:00 → GMT
Ireland runs IST in summer and GMT in winter: legally the reverse framing of the UK, same clock.
Israel Standard Time · Asia
04:45:50
Sunday, 27 September 2026
- abbreviation denotes
- +02:00
- in force right now
- IDT (UTC+03:00) · DST
- use in code
- Asia/Jerusalem
- next clock change
- 25 Oct 2026 01:00 → IST
Israel switches to IDT (UTC+3) in summer.
Right now this zone is on IDT, not IST. They are the same place at different times of year.
Use the IANA name, not the abbreviation
Python
from datetime import datetime
from zoneinfo import ZoneInfo
# right: an IANA zone carries the full history of rule changes
now = datetime.now(ZoneInfo("Asia/Kolkata"))
print(now.isoformat(), now.tzname())
# wrong: an abbreviation is not resolvable, and a hard-coded offset
# silently rots the next time the rules change
# now = datetime.now(timezone(timedelta(hours=...))) # don'tIST questions
What does IST stand for?
IST has 3 distinct meanings in active use: India Standard Time (+05:30, Asia/Kolkata); Irish Standard Time (+01:00, Europe/Dublin); Israel Standard Time (+02:00, Asia/Jerusalem). Which one applies depends entirely on who wrote the timestamp.
What time is it in IST right now?
India Standard Time: 07:15 on Sunday (IST); Irish Standard Time: 02:45 on Sunday (IST); Israel Standard Time: 04:45 on Sunday (IDT).
Which IANA timezone should I use instead of IST?
Asia/Kolkata for India Standard Time, Europe/Dublin for Irish Standard Time, Asia/Jerusalem for Israel Standard Time. Date libraries cannot resolve bare abbreviations, and an abbreviation carries no daylight-saving history, so a stored offset silently rots when a government changes the rules.