Difference Between GMT and IST

The difference between GMT and IST is as follows:

Features	Greenwich Mean Time (GMT)	Indian Standard Time (IST)
Location	The meridian passes through the Royal Observatory, Greenwich, London.	It passes through the middle of India near Allahabad.
Longitude Basis	Calculated at the Prime Meridian (0° longitude).	Calculated at 82.5° east longitude from the clock tower in Mirzapur.
Officially adopted on	GMT was officially adopted as the standard time at the International Meridian Conference held in Washington, D.C., in 1884.	IST was adopted as the standard time zone for India on January 1, 1906. Offically adopted on September 1, 1947.
Time Offset from UTC	UTC+00:00	UTC+05:30
Time Zone adopted by countries	Used internationally as a reference point for timekeeping worldwide	Offical timezone adopted by India and Sri Lanka.
Time Conversion	GMT = IST – 5 hours 30 minutes	IST = GMT + 5 hours 30 minutes
Daylight Saving Time (DST)	Not observed	Not observed
Challenge	An issue associated with Greenwich Mean Time is that it doesn’t always align precisely with the Sun’s zenith or noon due to the Earth’s variable angular velocity in its elliptical orbit and its axial tilt. This can lead to deviations in timekeeping accuracy.	One issue with Indian Standard Time is that it spans a wide geographic area(68°7’E to 97°25’E), leading to significant variations in sunrise and sunset times within India, impacting daylight hours across different regions.

Difference Between GMT And IST

Difference Between GMT And IST: GMT and IST are two distinct time zones, which are used to determine the local time at different places around the world. The time zone is a geographic region within which the same standard time is used. Greenwich Mean Time (GMT) is the time zone located at the Prime Meridian (0° longitude) in Greenwich, England. Indian Standard Time (IST) is the official time zone adopted by India. It has an offset of UTC +05:30, making it 5 hours and 30 minutes ahead of GMT. So Indian Standard Time is 5 hours and 30 minutes ahead of Greenwich Mean Time.

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