IST to GMT
-5h 30mIST
ISTSOURCEGMT
GMTGreen rows indicate typical business hours (9 AM - 5 PM)
IST and GMT on the World Map
The map below highlights the IST (India Standard Time) and GMT (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 GMT: Offsets, DST and Best Call Times
IST runs on India Standard Time (IST) at UTC+05:30. GMT runs on Greenwich Mean Time (GMT) at UTC+00:00. That puts IST 5 hours 30 minutes behind GMT — a difference of -5h 30m at the current offsets.
In practice, when it is 9:00 AM in IST it is 3:30 AM in GMT. Midnight in IST is 6:30 PM in GMT. Neither zone observes daylight saving time, so the offset between them stays constant all year.
IST to GMT time conversion table
| IST (IST) | GMT (GMT) | Day |
|---|---|---|
| 12:00 AM | 6:30 PM | previous day |
| 6:00 AM | 12:30 AM | same day |
| 7:00 AM | 1:30 AM | same day |
| 8:00 AM | 2:30 AM | same day |
| 9:00 AM | 3:30 AM | same day |
| 12:00 PM | 6:30 AM | same day |
| 3:00 PM | 9:30 AM | same day |
| 5:00 PM | 11:30 AM | same day |
| 6:00 PM | 12:30 PM | same day |
| 9:00 PM | 3:30 PM | same day |
Why people convert IST to GMT time
- Scheduling a call from IST to GMT: a 10:00 AM start in IST lands at 4:30 AM in GMT, so you can confirm the slot without doing the arithmetic yourself.
- Finding shared working hours: both IST and GMT are inside the 9-to-5 working day between 2:30 PM and 5:00 PM IST time (9:00 AM–11:30 AM GMT). That is roughly 2 hours 30 minutes of usable overlap.
- Watching a live event or market open: IST viewers need 3:30 AM in GMT to catch a 9:00 AM start there, and 5:30 AM if the event is anchored to IST.
- Always state the zone abbreviation, not just the hour. "3:00 PM IST" is unambiguous; "3 PM" across a -5h 30m gap is not.
- Block 2:30 PM–5:00 PM IST as the recurring meeting window if you work primarily from IST and need GMT colleagues present.
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 GMT
Both IST and GMT sit inside the 9 AM – 5 PM working day between 2:30 PM–5:00 PM IST, which is 9:00 AM–11:30 AM GMT. That gives roughly 2 hours and 30 minutes of shared time — the safest window for a live call or meeting.
Business hours overlap
IST and GMT overlap for about 2 hours during the working day — enough for meetings if you avoid the edges of the window.
IST is 5 hours 30 minutes behind GMT (IST UTC+05:30 → GMT UTC+00:00). The shared working window is 2:30 PM–5:00 PM IST. Remember to re-check around daylight-saving transitions.
🕐 Daylight Saving Time Info
IST
Does not observe DST
GMT
☀ 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 GMT?
IST (IST, UTC+05:30) is 5 hours 30 minutes behind GMT (GMT, UTC+00:00). The gap is currently -5h 30m.
How do I convert IST time to GMT time?
Add -5h 30m to IST local time. For example, 9:00 AM in IST is 3:30 AM in GMT.
What time is it in GMT right now?
GMT uses GMT at UTC+00:00. Use the live converter at the top of this page — it updates in real time and already accounts for the -5h 30m offset from IST.
What is the best time to call GMT from IST?
Call between 2:30 PM and 5:00 PM IST — that maps to 9:00 AM–11:30 AM GMT and keeps both parties inside the working day.
Which is behind, IST or GMT?
IST is 5 hours 30 minutes behind GMT. When it is 12:00 PM in IST it is 6:30 AM in GMT.
Does daylight saving time affect the IST–GMT difference?
Neither zone observes daylight saving time, so the -5h 30m offset between IST and GMT is fixed all year.
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 GMT?
Not normally. The -5h 30m gap only pushes the date over the previous day.
What is the time difference between IST and GMT?
GMT is -5h 30m from IST.
What timezone is IST in?
IST operates on its local timezone.
What timezone is GMT in?
GMT 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 GMT?
When it is 12:00 AM (midnight) in IST (IST), it is -5h 30m later in GMT (GMT).
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