Convert India Standard Time to Greenwich Mean Time
Instantly convert India Standard Time (IST) to Greenwich Mean Time (GMT) with our free online calculator.
India Standard Time
10:50:51 AM
Wed, Jun 24 (IST)
Greenwich Mean Time
05:20:51 AM
Wed, Jun 24 (GMT)
Convert a Specific Time
24-Hour Comparison
| IST | GMT |
|---|---|
| 12:00 AM | 6.5:00 PM(-1d) |
| 1:00 AM | 7.5:00 PM(-1d) |
| 2:00 AM | 8.5:00 PM(-1d) |
| 3:00 AM | 9.5:00 PM(-1d) |
| 4:00 AM | 10.5:00 PM(-1d) |
| 5:00 AM | 11.5:00 PM(-1d) |
| 6:00 AM | 0.5:00 AM |
| 7:00 AM | 1.5:00 AM |
| 8:00 AM | 2.5:00 AM |
| 9:00 AM | 3.5:00 AM |
| 10:00 AM | 4.5:00 AM |
| 11:00 AM | 5.5:00 AM |
| 12:00 PM | 6.5:00 AM |
| 1:00 PM | 7.5:00 AM |
| 2:00 PM | 8.5:00 AM |
| 3:00 PM | 9.5:00 AM |
| 4:00 PM | 10.5:00 AM |
| 5:00 PM | 11.5:00 AM |
| 6:00 PM | 0.5:00 PM |
| 7:00 PM | 1.5:00 PM |
| 8:00 PM | 2.5:00 PM |
| 9:00 PM | 3.5:00 PM |
| 10:00 PM | 4.5:00 PM |
| 11:00 PM | 5.5:00 PM |
How to Convert India Standard Time to Greenwich Mean Time
Formula
To convert India Standard Time (IST) to Greenwich Mean Time (GMT): Convert IST to GMT
About India Standard Time (IST)
India Standard Time (IST, IANA: Asia/Kolkata) is the civil time of the Republic of India and Sri Lanka, set at UTC+5:30 — one of the world's most populous 30-minute-offset time zones. India does not observe Daylight Saving Time per the Government of India directive (a brief DST trial in 1942-1945 during WWII was discontinued; subsequent proposals from 2010-2017 were rejected by the Indian Government citing minimal energy savings + agricultural sector disruption). IST is defined as the local mean solar time at 82.5°E longitude (passing through Shankargarh fort in Uttar Pradesh, with the reference clock at the National Physical Laboratory in New Delhi per the Indian Institute of Astrophysics). The 30-minute offset is preserved because India's east-west extent (68°E to 97°E) spans ~28° of longitude — approximately 2 hours of solar time — and the central meridian is most representative for a single unified zone. IST serves approximately 1.4 billion people in India + 22 million in Sri Lanka (Sri Lanka observes SLST = UTC+5:30, identical to IST). Major cities: Mumbai (12.5M), Delhi (16.8M, NCR 29M), Bengaluru (8.4M), Hyderabad (10M), Chennai (7M), Kolkata (4.5M), Ahmedabad (5.5M), Pune (3.1M). Affects: BSE/NSE stock exchanges, IPL Indian Premier League cricket schedules.
About Greenwich Mean Time (GMT)
Greenwich Mean Time (GMT, IANA: Europe/London) is the historic and current civil time of the United Kingdom (during winter), Ireland (during winter), Portugal mainland (during winter), Iceland (year-round), and most West African countries. GMT is set at UTC+0 — the time on the Prime Meridian (0° longitude) running through the Royal Observatory in Greenwich, southeast London. Established as the global time reference by the 1884 International Meridian Conference in Washington DC, GMT served as the world's primary civil-time reference from 1884 until 1972 when UTC (Coordinated Universal Time) was adopted as the new precision standard. The UK switches from GMT to British Summer Time (BST = UTC+1) at 01:00 GMT on the last Sunday of March and back to GMT at 02:00 BST on the last Sunday of October per EU Directive 2000/84/EC (UK retained this schedule after Brexit). GMT affects: London Stock Exchange (LSE) trading hours, BBC World Service broadcast time-stamps, all aviation NOTAMs and weather METARs which use UTC = GMT, and ICAO + IMO worldwide maritime/aviation coordination.