What IST means
India Standard Time is set at UTC+5:30 and covers the entire country. The IANA time zone identifier is Asia/Kolkata. It serves roughly 1.4 billion people, from Mumbai (population 12,691,836) to Delhi (11,034,555) to Bengaluru (8,495,492).
IST is maintained by the CSIR-National Physical Laboratory (NPL) in New Delhi, which operates atomic clocks and disseminates the official time through NTP servers and satellite.
IST is UTC+5:30, no DST
India does not observe daylight saving time. The offset is static year-round. This means:
- The sun rises and sets at predictable times relative to the clock
- No clock changes in March or October
- A single time zone across the entire country
The half-hour offset comes from the 82.5°E meridian, which passes through Mirzapur in Uttar Pradesh. That longitude was chosen in 1906 as a compromise between Calcutta Time (UTC+5:53:20) and Bombay Time (UTC+4:51).
IST vs other major time zones right now
The difference between IST and other zones shifts when those zones enter or leave daylight saving time. Here is how IST compares on two reference dates.
| City | Offset from IST (15 January 2026) | Offset from IST (15 July 2026) |
|---|---|---|
| New York | 10.5 hours behind | 9.5 hours behind |
| Los Angeles | 13.5 hours behind | 12.5 hours behind |
| London | 5.5 hours behind | 4.5 hours behind |
| Paris | 4.5 hours behind | 3.5 hours behind |
| Dubai | 1.5 hours behind | 1.5 hours behind |
| Singapore | 2.5 hours ahead | 2.5 hours ahead |
| Tokyo | 3.5 hours ahead | 3.5 hours ahead |
| Sydney | 5.5 hours ahead | 4.5 hours ahead |
| Johannesburg | 3.5 hours behind | 3.5 hours behind |
| São Paulo | 8.5 hours behind | 8.5 hours behind |
| Chicago | 11.5 hours behind | 10.5 hours behind |
The half-hour offset causes a common mental rounding error: people approximate to UTC+5 or UTC+6, then miss meetings by 30 minutes. Use a converter tool rather than doing the math in your head.
Why IST is always UTC+5:30
Three facts make this fixed offset unusual:
-
Only one time zone for a large country: India spans from 68°E to 97°E, which could justify two time zones. The "one-nation-one-time" policy keeps IST nationwide.
-
No DST ever adopted nationally: India experimented with daylight saving during wartime (1942-1945) and the 1962 Sino-Indian war, but never made it permanent.
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The 82.5°E meridian is the legal reference: Unlike most countries that use round-hour offsets (UTC+5, UTC+6), India's meridian sits between the two, producing the half-hour offset.
The next practical change for IST is not a clock change. It is the March equinox on 20 March 2026. On that day in Mumbai, sunrise will be at 06:43 and sunset at 18:49, giving 12 hours 6 minutes of daylight. By the June solstice (21 June 2026), Mumbai will see sunrise at 06:01 and sunset at 19:18, over 13 hours of daylight. The clock stays at UTC+5:30 through every season.