Asia/Kolkata time zone
5:41PMIST
ISTUTC+5:30+10 h 30 min vs New York (you)
No transitions: Asia/Kolkata stays on IST (UTC+5:30).
About Asia/Kolkata
Asia/Kolkata is the IANA time zone for India. It currently keeps India Standard Time (IST, UTC+5:30) all year.
Its principal location is Kolkata at 22.53° N, 88.37° E.
Abbreviations in use: IST. Offset page: UTC+5:30.
Rule for future years (POSIX TZ string)
IST-5:30
The standard time is called IST and is UTC+5:30. POSIX writes the offset with the opposite sign (west of Greenwich is positive), which is why the string says "-5:30". There is no daylight saving rule: the zone stays on this offset for every year after the end of its explicit transitions. Software that has no full tzdata copy, such as many embedded devices, can use this string directly as the TZ environment variable.
History of Asia/Kolkata since 1970
The record starts with local mean time (UTC+5:53), which ended on June 27, 1854. The first daylight saving time in the record is in 1941.
| Years | Clocks | Abbreviations |
|---|---|---|
| 1970 onward | UTC+5:30 all year | IST |
Before 1970
6 offset changes before 1970 in the record:
- Friday, December 31, 1869: UTC+5:53 → UTC+5:21 (MMT)
- Sunday, December 31, 1905: UTC+5:21 → UTC+5:30 (IST)
- Wednesday, October 1, 1941: UTC+5:30 → UTC+6:30, daylight saving time
- Friday, May 15, 1942: UTC+6:30 → UTC+5:30 (IST)
- Tuesday, September 1, 1942: UTC+5:30 → UTC+6:30, daylight saving time
- Monday, October 15, 1945: UTC+6:30 → UTC+5:30 (IST)
tzdata commits to accuracy from 1970 for every zone (zone1970.tab); earlier entries are historical research and may be incomplete.
Aliases and zones with the same clock
These older or country-specific IDs are links to Asia/Kolkata in tzdata. Their pages redirect here: Asia/Calcutta.
Other zones that keep exactly the same time under the current rules (but have a different history): Asia/Colombo.
Places on Asia/Kolkata
- MumbaiIN
- DelhiIN
- BengaluruIN
- HyderabadIN
- AhmedabadIN
- ChennaiIN
- KolkataIN
- SuratIN
- PuneIN
- JaipurIN
- KanpurIN
- Navi MumbaiIN
- LucknowIN
- NagpurIN
- CoimbatoreIN
- IndoreIN
- ThāneIN
- VadodaraIN
- BhopalIN
- RasapūdipalemIN
- Pimpri-ChinchwadIN
- PatnaIN
- KallakurichiIN
- LudhianaIN
Convert Kolkata time
Using Asia/Kolkata in code
Every major platform reads the same IANA ID. Store instants in UTC and convert with the ID at display time; never store a fixed offset for a place that has daylight saving time.
// JavaScript
new Date().toLocaleString('en-US', { timeZone: 'Asia/Kolkata' })
# Python 3.9+
from zoneinfo import ZoneInfo
from datetime import datetime
datetime.now(ZoneInfo('Asia/Kolkata'))
// Java
java.time.ZonedDateTime.now(java.time.ZoneId.of("Asia/Kolkata"))
// Go
loc, _ := time.LoadLocation("Asia/Kolkata")
time.Now().In(loc)
-- PostgreSQL
SELECT now() AT TIME ZONE 'Asia/Kolkata';
# Shell
TZ='Asia/Kolkata' datePlatforms ship their own copy of tzdata and update it on their own schedule. After a rule change, outputs can differ until the platform updates; this page uses tzdata 2026f.