Convert India Standard Time to Greenwich Mean Time (IST to GMT)

Understanding IST and GMT Time Zones

India Standard Time (IST)

India Standard Time is observed in undefined and uses the offset UTC+5.5. Major cities in this time zone include Mumbai, Delhi, Bangalore. This time zone serves a significant global region with important economic and cultural hubs.

Greenwich Mean Time (GMT)

Greenwich Mean Time operates at UTC+0, covering undefined. Key cities include London, Dublin, Lisbon. The 5.5-hour backward offset from IST means that when professionals in Mumbai start their workday at 9:00 AM, it is already 3:30 AM in London.

IST is also commonly referred to as India time, Indian time, Mumbai time, Delhi time. GMT is also known as London time, UK time, British time, England time. So if you are searching for India time to London time, this is the same conversion as IST to GMT.

Complete IST to GMT Conversion Table

The table below shows every two-hour increment converted from India Standard Time to Greenwich Mean Time. Business hours (9 AM – 5 PM) are highlighted for easy scheduling reference.

Times shown in 12-hour and 24-hour format. Last updated 2026-03-09.

Scheduling Between IST and GMT

When coordinating deliverables across IST and GMT, 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 IST and GMT 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 Mumbai and London

Flight times between Mumbai and London often appear misleading because of the time zone shift. A departure at 10:00 AM IST arriving at 7.5:00 PM GMT 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 IST and GMT, 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 IST to GMT conversion specifically: IST (UTC+5.5) does not observe DST, while GMT (UTC+0) does 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

• TimeAndDate.com — World Time Zones
• NIST — Official US Time Standard
• IANA Time Zone Database
• Wikipedia — Time Zone Abbreviations
• WorldTimeServer — Current Times Worldwide
• Royal Observatory Greenwich

Frequently Asked Questions