IST to United Kingdom
-4h 30mIST
ISTSOURCEUnited Kingdom
BSTGreen rows indicate typical business hours (9 AM - 5 PM)
IST and BST on the World Map
The map below highlights the IST (India Standard Time) and BST (Greenwich Mean Time) timezone regions across the globe.
IST – India Standard Time
UTC+05:30India Standard Time (IST) is the time zone for India and Sri Lanka, 5 hours and 30 minutes ahead of UTC.
- •India is 10 hours 30 minutes ahead of EST and 5 hours 30 minutes ahead of GMT.
- •India uses a single time zone despite spanning 30° of longitude.
- •IST is one of only a handful of time zones with a 30-minute offset.
- •IST is the most populous single time zone in the world with over 1.4 billion people.
- •The Bombay Stock Exchange (BSE) and National Stock Exchange (NSE) operate on IST.
GMT – Greenwich Mean Time
UTC+00:00Greenwich Mean Time (GMT) is the mean solar time at the Royal Observatory in Greenwich, London. It is the same as UTC+00:00.
- •GMT is based on the Prime Meridian (0° longitude) passing through Greenwich, London.
- •The Royal Observatory in Greenwich has been the reference point for GMT since 1884.
- •GMT and UTC are often used interchangeably, but UTC is based on atomic clocks.
- •Iceland uses GMT year-round and never observes daylight saving time.
- •The UK switches from GMT to BST (British Summer Time) in late March each year.
IST vs United Kingdom: Offsets, DST and Best Call Times
IST runs on India Standard Time (IST) at UTC+05:30. United Kingdom runs on British Summer Time (BST) at UTC+01:00, also currently on daylight saving time. That puts IST 4 hours 30 minutes behind United Kingdom — a difference of -4h 30m at the current offsets.
In practice, when it is 9:00 AM in IST it is 4:30 AM in United Kingdom. Midnight in IST is 7:30 PM in United Kingdom.United Kingdom observes daylight saving time while IST does not, so the gap narrows or widens by an hour part of the year.
IST to United Kingdom time conversion table
| IST (IST) | United Kingdom (BST) | Day |
|---|---|---|
| 12:00 AM | 7:30 PM | previous day |
| 6:00 AM | 1:30 AM | same day |
| 7:00 AM | 2:30 AM | same day |
| 8:00 AM | 3:30 AM | same day |
| 9:00 AM | 4:30 AM | same day |
| 12:00 PM | 7:30 AM | same day |
| 3:00 PM | 10:30 AM | same day |
| 5:00 PM | 12:30 PM | same day |
| 6:00 PM | 1:30 PM | same day |
| 9:00 PM | 4:30 PM | same day |
Why people convert IST to United Kingdom time
- Scheduling a call from IST to United Kingdom: a 10:00 AM start in IST lands at 5:30 AM in United Kingdom, so you can confirm the slot without doing the arithmetic yourself.
- Finding shared working hours: both IST and United Kingdom are inside the 9-to-5 working day between 1:30 PM and 5:00 PM IST time (9:00 AM–12:30 PM BST). That is roughly 3 hours 30 minutes of usable overlap.
- Keeping family and friends in sync: knowing that 8:00 PM in IST is 3:30 PM in United Kingdom makes it easy to avoid calling at 3 AM.
- Always state the zone abbreviation, not just the hour. "3:00 PM IST" is unambiguous; "3 PM" across a -4h 30m gap is not.
- Block 1:30 PM–5:00 PM IST as the recurring meeting window if you work primarily from IST and need United Kingdom colleagues present.
- United Kingdom: Clocks fall back on Sun, Oct 25, 2026. Any meeting series spanning that date will shift by an hour in local time.
About IST (India Standard Time)
India Standard Time (IST) is the time observed throughout India and Sri Lanka. It is based on the 82.5°E meridian, passing through Mirzapur in Uttar Pradesh. India uses a single time zone despite spanning roughly 30° of longitude, which has been debated. IST does not observe daylight saving time. India is the world's most populous country, making IST one of the most-used time zones globally. The IT outsourcing industry and call centers operate primarily on IST, making the EST-to-IST conversion one of the most searched timezone conversions.
About GMT (Greenwich Mean Time)
Greenwich Mean Time (GMT) is the clock time at the Royal Observatory in Greenwich, London, which sits on the Prime Meridian (0° longitude). GMT serves as the reference point from which all other time zones are calculated. The United Kingdom uses GMT during winter months and switches to British Summer Time (BST, UTC+01:00) from late March to late October. Several West African nations use GMT year-round. GMT is often used interchangeably with UTC (Coordinated Universal Time), although technically they are different – UTC is based on atomic clocks while GMT is based on Earth's rotation.
Best time to call between IST and United Kingdom
Both IST and United Kingdom sit inside the 9 AM – 5 PM working day between 1:30 PM–5:00 PM IST, which is 9:00 AM–12:30 PM BST. That gives roughly 3 hours and 30 minutes of shared time — the safest window for a live call or meeting.
Business hours overlap
IST and United Kingdom overlap for about 3 hours during the working day — enough for meetings if you avoid the edges of the window.
IST is 4 hours 30 minutes behind United Kingdom (IST UTC+05:30 → BST UTC+01:00). The shared working window is 1:30 PM–5:00 PM IST. Remember to re-check around daylight-saving transitions.
🕐 Daylight Saving Time Info
IST
Does not observe DST
United Kingdom
☀ Currently in DST
Standard: UTC+00:00 · DST: UTC+01:00
Clocks fall back on Sun, Oct 25, 2026
Learn More About Time
Dive deeper into the fascinating world of timekeeping, time zones, and how they shape our global society:
Frequently Asked Questions
What is the time difference between IST and United Kingdom?
IST (IST, UTC+05:30) is 4 hours 30 minutes behind United Kingdom (BST, UTC+01:00). The gap is currently -4h 30m.
How do I convert IST time to United Kingdom time?
Add -4h 30m to IST local time. For example, 9:00 AM in IST is 4:30 AM in United Kingdom.
What time is it in United Kingdom right now?
United Kingdom uses BST at UTC+01:00. Use the live converter at the top of this page — it updates in real time and already accounts for the -4h 30m offset from IST.
What is the best time to call United Kingdom from IST?
Call between 1:30 PM and 5:00 PM IST — that maps to 9:00 AM–12:30 PM BST and keeps both parties inside the working day.
Which is behind, IST or United Kingdom?
IST is 4 hours 30 minutes behind United Kingdom. When it is 12:00 PM in IST it is 7:30 AM in United Kingdom.
Do IST and United Kingdom use different time zones?
IST uses IST at UTC+05:30, while United Kingdom (United Kingdom) uses BST at UTC+01:00. The IANA identifiers are Asia/Kolkata and Europe/London.
Does daylight saving time affect the IST–United Kingdom difference?
Yes at the moment: United Kingdom is on daylight saving time and IST is not, so the -4h 30m gap shifts by an hour when exactly one of them changes clocks.
Which other cities share IST's time zone?
IST also covers Mumbai, Delhi, Bangalore, Kolkata, Chennai, Hyderabad, Pune, Ahmedabad and 4 more.
Which countries use IST, IST's zone?
IST is used in India, Sri Lanka.
Is there a day difference between IST and United Kingdom?
Not normally. The -4h 30m gap only pushes the date over the previous day.
What is the time difference between IST and United Kingdom?
United Kingdom is -4h 30m from IST.
What timezone is IST in?
IST operates on its local timezone.
What timezone is United Kingdom in?
United Kingdom operates on its local timezone.
Which countries use IST (India Standard Time)?
IST is used in India, Sri Lanka.
Does IST observe daylight saving time?
No, IST does not observe daylight saving time and remains at UTC+05:30 year-round.
What are some interesting facts about IST?
India is 10 hours 30 minutes ahead of EST and 5 hours 30 minutes ahead of GMT. India uses a single time zone despite spanning 30° of longitude.
Which cities are in the GMT timezone?
Major cities in the GMT timezone include London, Dublin, Lisbon, Accra, Reykjavik, Edinburgh, Casablanca, Dakar.
What is the UTC offset for GMT?
Greenwich Mean Time (GMT) is at UTC+00:00. During daylight saving time, it shifts to BST.
What should I know about the GMT timezone?
GMT is based on the Prime Meridian (0° longitude) passing through Greenwich, London. The Royal Observatory in Greenwich has been the reference point for GMT since 1884.
When is it midnight in IST, what time is it in United Kingdom?
When it is 12:00 AM (midnight) in IST (IST), it is -4h 30m later in United Kingdom (GMT).
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