Time Zone History

India time zone history

Its standard time, UTC+5:30, is one of only 14 offsets among the 312 zones that are not a whole number of hours from UTC. Kolkata left local mean time (UTC+5:53:28) in 1854, the fourth-earliest switch of the 298 zones with local mean time in the record. On standard time, clocks at Kolkata run 23 minutes behind local mean solar time, the second-largest gap of the 21 zones in Asia whose clocks run behind the sun.

UTC+5:30

Standard time is UTC+5:30 (IST) all year under the current rules.

tz database name Asia/Kolkata

Convert a time from India

UTC+5:30 every day since 1970

UTC+5:21:10: 9 minutes behind today’s standard timeUTC+5:30: today’s standard timeUTC+5:53:20, UTC+5:53:28: ahead of today’s standard timeUTC+6:30: 1 hour ahead of today’s standard timeUTC+5:21:10: 9 minutes behindtoday’s standard timeUTC+5:30: today’s standard timeUTC+5:53:20, UTC+5:53:28: ahead oftoday’s standard timeUTC+6:30: 1 hour ahead of today’sstandard time

How to read this chart

Before 1970

18501870189019101930195019701850189019301970
JanFebMarAprMayJunJulAugSepOctNovDec1970198019902000201020202028JFMAMJJASOND1970198019902000201020202028

Standard time changes

DateChangeNew standard timeClock label
Before 1970
June 28, 1854Local mean time (UTC+5:53:28) replacedUTC+5:53:20HMT
January 1, 1870Standard time back 32 minutesUTC+5:21:10MMT
January 1, 1906Standard time forward 9 minutesUTC+5:30IST

Daylight saving periods

YearsClocks go forwardClocks go backShift and labels
1941October 1not that year1 hour
1942September 1May 151 hour
1945not that yearOctober 151 hour

Also on UTC+5:30

Sri Lanka.

Clocks next door since 1970

  • Bangladesh (248 km): usually 30 minutes ahead; different on 195 days in 2009.
  • Bhutan (564 km): usually 30 minutes ahead; different on 6,482 days in 1970–1987.
  • Nepal (653 km): usually 15 minutes ahead; different on 5,844 days in 1970–1985.
  • Myanmar (1,037 km): always 1 hour ahead.
  • Thailand (1,612 km): always 1 hour 30 minutes ahead.

How it compares

India has kept UTC+5:30 since 1906, with no clock changes since 1970.