GMT to IST Converter
Understanding GMT and IST Time Zones
Greenwich Mean Time (GMT)
Greenwich Mean Time is observed in undefined and uses the offset UTC+0. Major cities in this time zone include London, Dublin, Lisbon. This time zone covers parts of Europe and/or Africa, home to major financial and cultural centers.
India Standard Time (IST)
India Standard Time operates at UTC+5.5, covering undefined. Key cities include Mumbai, Delhi, Bangalore. The 5.5-hour forward offset from GMT means that when professionals in London start their workday at 9:00 AM, it is already 2:30 PM in Mumbai.
GMT is also commonly referred to as London time, UK time, British time, England time. IST is also known as India time, Indian time, Mumbai time, Delhi time. So if you are searching for London time to India time, this is the same conversion as GMT to IST.
Complete GMT to IST Conversion Table
The table below shows every two-hour increment converted from Greenwich Mean Time to India Standard Time. Business hours (9 AM – 5 PM) are highlighted for easy scheduling reference.
| GMT (Greenwich Mean Time) | IST (India Standard Time) |
|---|---|
| 12:00 AM (00:00) | 5:30 AM (05:30) |
| 2:00 AM (02:00) | 7:30 AM (07:30) |
| 4:00 AM (04:00) | 9:30 AM (09:30) |
| 6:00 AM (06:00) | 11:30 AM (11:30) |
| 8:00 AM (08:00) | 1:30 PM (13:30) |
| 10:00 AM (10:00) | 3:30 PM (15:30) |
| 12:00 PM (12:00) | 5:30 PM (17:30) |
| 2:00 PM (14:00) | 7:30 PM (19:30) |
| 4:00 PM (16:00) | 9:30 PM (21:30) |
| 6:00 PM (18:00) | 11:30 PM (23:30) |
| 8:00 PM (20:00) | 1:30 AM (01:30) (next day) |
| 10:00 PM (22:00) | 3:30 AM (03:30) (next day) |
Times shown in 12-hour and 24-hour format. Last updated 2026-03-09.
Scheduling Between GMT and IST
When coordinating deliverables across GMT and IST, set deadlines in the earlier time zone to avoid end-of-day confusion. A "5 PM deadline" should specify which zone to prevent missed deliveries due to the 5.5-hour offset.
The moderate 5.5-hour gap between GMT and IST means that there is a partial overlap of business hours. Teams can typically find a 3–4 hour window that works for both sides without requiring anyone to work outside normal hours.
Travel Between London and Mumbai
Flight times between London and Mumbai often appear misleading because of the time zone shift. A departure at 10:00 AM GMT arriving at 7.5:00 PM IST may look long, but remember to factor in the 5.5-hour offset.
Medical experts recommend allowing approximately one day of adjustment per hour of time difference. For the 5.5-hour shift between GMT and IST, plan for about 5.5 days to fully acclimate.
Daylight Saving Time Considerations
Countries near the equator — including Singapore, most of Africa, and parts of South America — do not observe DST, making their offsets constant year-round. This simplifies scheduling compared to US or European zones.
For the GMT to IST conversion specifically: GMT (UTC+0) observes DST, while IST (UTC+5.5) does not observe DST. This means the offset between them changes by one hour seasonally — the usual 5.5-hour gap becomes 4.5 or 6.5 hours during DST transitions.
Related Time Zone Conversions
References & Resources
Frequently Asked Questions
GMT (Greenwich Mean Time) is 5.5 hours behind IST (India Standard Time). GMT is UTC+0 and IST is UTC+5.5.
When it is 12:00 PM (noon) in GMT, it is 5:30 PM in IST.
The best overlap for business hours is approximately 2:00 PM to 10:00 PM IST, which corresponds to 9:00 AM to 5:00 PM in GMT.
Countries near the equator — including Singapore, most of Africa, and parts of South America — do not observe DST, making their offsets constant year-round. This simplifies scheduling compared to US or European zones.