IST to GMT Converter

Use this IST to GMT Converter to convert India Standard Time to UK time for meetings, remote work, calls, interviews, and scheduling with London and the UK.

Quick Answer: Indian Standard Time (IST) is UTC+5:30. Greenwich Mean Time (GMT) is UTC+0. GMT is 5 hours and 30 minutes behind IST. During UK Summer Time (BST, UTC+1), the difference narrows to 4 hours and 30 minutes. To convert IST to GMT, subtract 5 hours and 30 minutes — or subtract 4 hours and 30 minutes during UK summer.

Current Time Difference Between IST and GMT Right Now

The live converter above shows the exact current time in both India and the UK right now, calculated automatically from your device’s clock. At any given moment, the UK is either 4 hours 30 minutes or 5 hours 30 minutes behind India — never anything in between, and never ahead. If you are checking “what time is it in London compared to India 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 the IST to GMT Difference Changes Throughout the Year

This is the most important thing to understand when converting IST to UK time — and the reason many converters give you the wrong answer for part of the year.

IST (Indian Standard Time) is UTC+5:30, fixed year-round. India does not observe Daylight Saving Time, so IST never changes regardless of the season.

GMT (Greenwich Mean Time) is UTC+0:00. This is the offset the UK uses only 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 switches to BST. Most people in India still say “GMT” when they mean UK time — but for roughly seven months of the year, UK time is actually BST, not GMT.

Because India’s IST is fixed while the UK side changes, the IST–GMT gap is not the same all year:

The converter above detects the correct UK offset based on the date you enter, so your result is always accurate.

IST to GMT Conversion Table

These cover the most commonly searched India-to-UK time conversions. For exact results by date, use the converter above.

What Is IST (Indian Standard Time)?

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

India adopted its national time zone in 1905, aligning to the 82.5° East meridian through Allahabad, Uttar Pradesh. The resulting UTC+5:30 offset is a half-hour increment rather than a whole hour — one of only a few such offsets in the world. India has never observed Daylight Saving Time. IST is UTC+5:30 every single day of the year, with no exceptions.

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

What Is GMT (Greenwich Mean Time)?

Greenwich Mean Time (GMT) is UTC+0:00, the time zone at the Prime Meridian passing through Greenwich, London. The UK observes GMT during winter — from the last Sunday in October through the last Sunday in March.

From late March through late October, the UK switches to British Summer Time (BST, UTC+1). This schedule continues to follow the EU-derived Summer Time Order even after Brexit.

When people in India search “IST to GMT,” they almost always mean whichever UK offset is currently active — GMT in winter, BST in summer. This converter handles both automatically.

Other countries on GMT/IST-relevant European time: Ireland (same schedule as the UK), Portugal (Lisbon follows GMT/WEST on the same dates), and Iceland (UTC+0 year-round, no summer shift).

Best Times to Schedule Meetings Between IST and GMT

The IST–GMT gap is the smallest among the major India-to-West conversions (4.5 to 5.5 hours), which means a genuine overlap window exists during normal working hours on both sides — a major practical advantage of India-UK collaboration over India-US.

Recommended window: 1:00 PM – 6:00 PM IST. This equals 6:30 AM – 12:30 PM GMT (or 7:30 AM – 1:30 PM BST) — both sides comfortably in working hours across this entire range. India-UK scheduling is significantly easier than India-US, since both regions share several hours of genuine business-hours overlap every single day.

How the Converter Calculates IST to GMT

The converter processes your IST input in the following order:

1. Take the India date and time you enter
2. Convert IST (UTC+5:30) to UTC by subtracting 5 hours 30 minutes
3. Check whether the resulting date falls within UK Summer Time (last Sunday in March through last Sunday in October in UK local time)
4. Apply the correct UK offset — UTC+0 for GMT, UTC+1 for BST
5. Display the result with both the UK time and the applicable offset

This date-aware approach is why the converter gives accurate results year-round, unlike simple converters that always subtract the same fixed number of hours.

The formulas:

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

Need to Convert GMT to IST Instead?

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

→ GMT to IST Converter

Quick reference:

IST to GMT — Frequently Asked Questions

What is the time difference between IST and GMT? GMT is 5 hours and 30 minutes behind IST (Indian Standard Time, UTC+5:30). During UK Summer Time (BST, UTC+1), which runs from the last Sunday in March through the last Sunday in October, GMT/BST is 4 hours and 30 minutes behind IST. India’s IST is fixed at UTC+5:30 year-round — the seasonal change comes entirely from the UK switching between GMT and BST.

What is 8 PM IST in GMT? 8:00 PM IST equals 2:30 PM GMT during UK winter (true GMT). During UK summer (BST), 8:00 PM IST equals 3:30 PM BST.

What is 9 PM IST in GMT? 9:00 PM IST equals 3:30 PM GMT during UK winter. During UK summer (BST), 9:00 PM IST equals 4:30 PM BST.

What is 10 PM IST in GMT? 10:00 PM IST equals 4:30 PM GMT during UK winter. During UK summer (BST), 10:00 PM IST equals 5:30 PM BST.

What is 7 PM IST in GMT? 7:00 PM IST equals 1:30 PM GMT during UK winter. During UK summer (BST), 7:00 PM IST equals 2:30 PM BST. This falls within the best IST-to-GMT meeting overlap window.

What is midnight (12 AM) IST in GMT? 12:00 AM IST equals 6:30 PM GMT on the previous calendar day during UK winter. During UK summer (BST), midnight IST equals 7:30 PM BST on the previous day.

Why does the UK offset keep changing from India’s perspective? The UK alternates between GMT (UTC+0) and BST (UTC+1) due to Summer Time, observed 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 permanently. From India’s perspective, the UK simply shifts one hour earlier for roughly seven months of the year.

How do I convert IST to GMT manually? To convert IST to true GMT, subtract 5 hours and 30 minutes from your IST time. During UK Summer Time (BST, late March through late October), subtract only 4 hours and 30 minutes instead. Most results stay on the same calendar day, except for IST times before roughly 5:30 AM, which land on the previous day in the UK.

What is the GMT equivalent of 5:30 AM IST? 5:30 AM IST equals 12:00 AM (midnight) GMT during UK winter — the same calendar day. During UK summer (BST), 5:30 AM IST equals 1:00 AM BST, also the same calendar day.

What time should I schedule a call from India for a UK morning meeting? For a 9:00 AM GMT meeting in the UK during winter, join at 2:30 PM IST. For a 9:00 AM BST meeting during UK summer, join at 1:30 PM IST. The 1:00 PM – 3:00 PM IST window generally covers UK morning-to-midday start times (7:30 AM – 9:30 AM UK time) year-round.

What is 11 AM IST in GMT? 11:00 AM IST equals 5:30 AM GMT during UK winter. During UK summer (BST), 11:00 AM IST equals 6:30 AM BST.

What is 12 PM IST in GMT? 12:00 PM (noon) IST equals 6:30 AM GMT during UK winter. During UK summer (BST), noon IST equals 7:30 AM BST.

What is 1 PM IST in GMT? 1:00 PM IST equals 7:30 AM GMT during UK winter. During UK summer (BST), 1:00 PM IST equals 8:30 AM BST.

What is 6 PM IST in GMT? 6:00 PM IST equals 12:30 PM GMT during UK winter. During UK summer (BST), 6:00 PM IST equals 1:30 PM BST.

Is London time behind India? Yes. London (UK time) is always behind India (IST) — by 5 hours and 30 minutes during UK winter (true GMT), or by 4 hours and 30 minutes during UK summer (BST). India is never behind London, because India does not observe Daylight Saving Time while the UK does.

What time is it in London right now compared to India? London is always either 4 hours 30 minutes or 5 hours 30 minutes behind India, 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’s IST (UTC+5:30) never changes, so only the UK side determines which gap applies on a given date. Use the live converter above for the exact current time in both locations.

Does the IST to GMT time difference change during the year? Yes, but only because of the UK side. The IST to GMT 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).

What is 2 PM IST in GMT? 2:00 PM IST equals 8:30 AM GMT during UK winter. During UK summer (BST), 2:00 PM IST equals 9:30 AM BST. This is comfortably within the best India-UK overlap window.

About IST and GMT

Indian Standard Time (IST) is UTC+5:30 — one of a small number of world time zones with a half-hour offset. India uses a single time zone despite spanning roughly 30 degrees of longitude, a policy in place since 1905. IST is fixed and never adjusts for daylight saving. According to the IANA Time Zone Database, the official identifier for Indian Standard Time is Asia/Kolkata.

Greenwich Mean Time is the time zone at the Prime Meridian, identified in the IANA Time Zone Database as Europe/London for UK time. 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. India and the UK share a historical connection through the British Raj, during which Indian Standard Time was originally established relative to GMT — though IST’s UTC+5:30 offset has remained fixed and independent of UK clock changes since 1905.

Author & Methodology

Author: CalculatorGeek Editorial Team Reviewed by: CalculatorGeek Technical Review Team Last reviewed: June 2026 Methodology: This converter uses IANA timezone identifiers (Asia/Kolkata for IST, Europe/London for UK time), date-aware offset logic, and UK Summer Time rules to correctly show whether UK time is GMT (UTC+0) or BST (UTC+1) for any date entered.

References:

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

Also useful:

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