GMT to IST Converter

Use this GMT to IST Converter to convert Greenwich Mean Time to India Standard Time for meetings, remote work, webinars, interviews, and international calls.

Quick Answer: Greenwich Mean Time (GMT) is UTC+0. Indian Standard Time (IST) is UTC+5:30. IST is 5 hours and 30 minutes ahead of GMT. During UK summer — when the UK observes British Summer Time (BST, UTC+1) — the difference narrows to 4 hours and 30 minutes. India does not observe Daylight Saving Time, so IST is fixed year-round.

Current Time Difference Between GMT and IST Right Now

The live converter above shows the exact current time in both the UK and India right now, calculated automatically from your device’s clock. At any given moment, India is either 4 hours 30 minutes or 5 hours 30 minutes ahead of the UK — never anything in between, and never in the opposite direction. If you are checking “what time is it in India compared to London right now,” the answer is always one of these two values depending on whether the UK is currently observing GMT or BST. The section below explains exactly which one applies and when it changes.

Why GMT to IST Is Either 4:30 or 5:30 Hours

This is the most common confusion with this conversion — and the reason most converters give you the wrong answer for part of the year.

GMT (Greenwich Mean Time) is UTC+0:00. The UK observes GMT during winter — from the last Sunday in October through the last Sunday in March.

BST (British Summer Time) is UTC+1:00. From the last Sunday in March through the last Sunday in October, the UK moves to BST. Many people say “GMT” year-round when referring to UK time — but for roughly seven months of the year, UK time is actually BST, not GMT.

IST (Indian Standard Time) is UTC+5:30, fixed year-round. India has never observed Daylight Saving Time.

This creates two different answers depending on the time of year:

The converter above automatically detects which offset applies based on the date you select — so your result is always correct.

GMT to IST Conversion Table

These cover the most commonly searched time combinations. For any specific date, use the converter above.

What Is GMT (Greenwich Mean Time)?

Greenwich Mean Time (GMT) is UTC+0, the time zone at the Prime Meridian (0° longitude) passing through Greenwich, London. It is the historical reference point from which all other time zones are measured.

The UK observes GMT only during winter. From late March through late October, the UK switches to British Summer Time (BST, UTC+1). When people search “GMT to IST,” they usually mean current UK time — which is GMT in winter and BST in summer. This converter defaults to real-world UK time, auto-detecting GMT or BST based on the date.

Other countries that observe UTC+0 year-round (true GMT, no summer shift) include Iceland, Senegal, and parts of West Africa.

What Is IST (Indian Standard Time)?

Indian Standard Time (IST) is UTC+5:30 — exactly 5 hours and 30 minutes ahead of Coordinated Universal Time. It is the single time zone used across all of India.

India adopted a unified national time zone in 1905, aligned to the 82.5° East meridian passing through Allahabad, Uttar Pradesh. This produces the unusual 30-minute offset rather than a whole-hour increment. India has never observed Daylight Saving Time — IST stays at UTC+5:30 every day of the year.

Key cities on IST: Mumbai, New Delhi, Bengaluru, Hyderabad, Chennai, Kolkata, Pune, Ahmedabad.

Best Times to Schedule Meetings Between GMT and IST

The GMT–IST gap is the smallest among the major UK/US–India conversions (4.5 to 5.5 hours), which means a genuine overlap window exists during normal working hours on both sides — unlike the PST or EST pairings.

Recommended window: 9:00 AM – 1:00 PM UK time. This equals 1:30 PM – 6:30 PM IST — both sides comfortably in working hours for most of this window. This is by far the easiest scheduling pair among the conversions covered on this site, and a major practical advantage of UK–India collaboration over US–India.

How the Converter Calculates GMT to IST

The converter follows this logic for every time you enter:

1. Take the UK date and time you input
2. Check whether that date falls inside UK Summer Time (last Sunday in March through last Sunday in October)
3. Apply the correct UK offset — UTC+0 for GMT, UTC+1 for BST
4. Convert to UTC
5. Add 5 hours and 30 minutes (UTC+5:30) to get IST

This is more accurate than adding a fixed 5:30 to every date. A converter that always adds 5:30 gives you the wrong answer for roughly seven months of the year, whenever the UK is on BST.

The formulas:

• True GMT → IST: add 5 hours 30 minutes
• BST → IST: add 4 hours 30 minutes

Need to Convert IST to GMT Instead?

If you are starting from India time and need the UK equivalent, use the reverse converter:

→ IST to GMT Converter

Quick reference:

GMT to IST — Frequently Asked Questions

What is the time difference between GMT and IST? The time difference between Greenwich Mean Time (GMT) and Indian Standard Time (IST) is 5 hours and 30 minutes — IST is ahead. During UK Summer Time (BST, last Sunday in March through last Sunday in October), the difference narrows to 4 hours and 30 minutes because the UK shifts to UTC+1 while India stays at UTC+5:30 year-round.

What is 9 AM GMT in IST? 9:00 AM true GMT equals 2:30 PM IST. During British Summer Time (BST), 9:00 AM UK time equals 1:30 PM IST. The correct answer depends on the date — use the converter above for date-accurate results.

What is 10 AM GMT in IST? 10:00 AM true GMT equals 3:30 PM IST. During BST, 10:00 AM UK time equals 2:30 PM IST.

What is 12 PM (noon) GMT in IST? 12:00 PM true GMT equals 5:30 PM IST. During BST, noon UK time equals 4:30 PM IST.

What is 3 PM GMT in IST? 3:00 PM true GMT equals 8:30 PM IST. During BST, 3:00 PM UK time equals 7:30 PM IST.

What is 6 PM GMT in IST? 6:00 PM true GMT equals 11:30 PM IST. During BST, 6:00 PM UK time equals 10:30 PM IST.

Why does GMT to IST sometimes show 4 hours 30 minutes instead of 5 hours 30 minutes? This happens when the UK is on BST (British Summer Time, UTC+1) rather than true GMT (UTC+0). The UK observes BST from the last Sunday in March through the last Sunday in October. India does not change its clocks, so IST stays at UTC+5:30 year-round — meaning the gap shrinks during UK summer.

Why is there a 30-minute increment in the GMT to IST difference? India’s UTC+5:30 offset includes a 30-minute increment because IST was established to align with the 82.5° East meridian passing through Allahabad. India chose a single national time zone rather than splitting the country, and the geographic midpoint of the country falls at a longitude that corresponds to a half-hour offset. True GMT is UTC+0:00, so the total gap is 5 hours 30 minutes (or 4 hours 30 minutes during BST).

Does India observe Daylight Saving Time? No. Indian Standard Time (IST) is UTC+5:30 year-round. India has never observed Daylight Saving Time and has no seasonal clock changes. This is why the GMT–IST difference changes seasonally — the change is entirely on the UK side, not the Indian side.

What cities use Greenwich Mean Time? Major cities on GMT during UK winter include London, Manchester, Edinburgh, Birmingham, Glasgow, Dublin (Ireland follows the same GMT/IST schedule under a different name), and Lisbon (Portugal). During UK summer (late March through late October), these cities observe BST (UTC+1). Some countries observe UTC+0 year-round without a summer shift, including Iceland and Senegal.

Is “GMT” the same as UK time year-round? Not exactly. “GMT” is often used loosely to mean “UK time” in everyday speech, but technically the UK is only on true GMT (UTC+0) during winter. From late March through late October, UK time is BST (UTC+1). When people say “GMT to IST” they usually mean whichever UK offset is currently active — which is why this converter defaults to real-world UK time rather than fixed UTC+0.

Is GMT the same as UTC? For practical time conversion purposes, yes. GMT and UTC (Coordinated Universal Time) are both UTC+0 and give identical results when converting to IST. The distinction matters mainly in technical and scientific contexts — UTC is maintained by atomic clocks and is the modern global standard, while GMT is the historical solar-time-based name still used colloquially for UK winter time.

What is 8 PM GMT in IST? 8:00 PM true GMT equals 1:30 AM IST the following day. During BST, 8:00 PM UK time equals 12:30 AM IST the following day.

What is 9 PM GMT in IST? 9:00 PM true GMT equals 2:30 AM IST the following day. During BST, 9:00 PM UK time equals 1:30 AM IST the following day.

What is 11 PM GMT in IST? 11:00 PM true GMT equals 4:30 AM IST the following day. During BST, 11:00 PM UK time equals 3:30 AM IST the following day.

Is India 5 hours ahead of the UK? Roughly, yes — but the exact figure depends on the season. India (IST) is 5 hours and 30 minutes ahead of the UK during UK winter (true GMT), or 4 hours and 30 minutes ahead during UK summer (BST). The relationship is always in this direction; the UK is never ahead of India.

What time is it in India right now compared to London? India is always either 4 hours 30 minutes or 5 hours 30 minutes ahead of London, depending on whether London is currently on Greenwich Mean Time (GMT, UTC+0, used late October through late March) or British Summer Time (BST, UTC+1, used late March through late October). India does not observe Daylight Saving Time, so its UTC+5:30 offset never changes — only the UK side shifts. Use the live converter above for the exact current time in both locations.

Does the GMT to IST time difference change during the year? Yes, but only because of the UK side. The GMT to IST difference is 5 hours 30 minutes when the UK is on true GMT (UTC+0, late October through late March) and 4 hours 30 minutes when the UK is on BST (UTC+1, late March through late October). India’s offset stays at UTC+5:30 every day of the year. The transition dates are the last Sunday in March (gap narrows to 4:30) and the last Sunday in October (gap widens back to 5:30).

About GMT and IST

Greenwich Mean Time (GMT) is the time zone at the Prime Meridian, historically the basis for global timekeeping and still used as the UK’s winter time zone. The UK alternates between GMT (UTC+0:00) from late October through late March and British Summer Time (UTC+1:00) from late March through late October, under the EU-derived Summer Time Order still followed by the UK post-Brexit. Common alternative names for UK time include UK Time, London Time, and (loosely) UTC.

Indian Standard Time (IST) is UTC+5:30 — a half-hour offset that places India 5 hours and 30 minutes ahead of Coordinated Universal Time. India uses a single time zone across its entire territory and has done so since 1905. According to the IANA Time Zone Database — the official global standard used by all major operating systems and browsers — India Standard Time is identified by the timezone identifier Asia/Kolkata, while UK time is identified as Europe/London.

The IANA Time Zone Database contains the complete historical record of UK GMT/BST transition dates, which have shifted slightly over past decades but currently follow the last-Sunday-in-March and last-Sunday-in-October pattern.

Author & Methodology

Author: CalculatorGeek Editorial Team Reviewed by: CalculatorGeek Technical Review Team Last reviewed: June 2026 Methodology: This converter uses IANA timezone identifiers (Europe/London for UK time, Asia/Kolkata for IST), date-aware offset logic, and India Standard Time rules to correctly handle the GMT/BST distinction that most static converters ignore.

References:

• IANA Time Zone Database — official source for UTC offsets, timezone identifiers, and DST transition rules worldwide
• MDN Web Docs — Intl.DateTimeFormat — browser implementation of IANA timezone formatting using Europe/London and Asia/Kolkata
• India Standard Time — Wikipedia — confirms IST is UTC+5:30 with no DST observance
• UK Summer Time — GOV.UK — official UK Government source for GMT/BST transition dates

Also useful:

• IST to GMT Converter
• EST to IST Converter
• PST to IST Converter
• All Time Zone Converters