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IST to GMT Converter

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Quick answer

IST to GMT conversion table

IST is 5 hours 30 minutes ahead of GMT, or IST is 4 hours 30 minutes ahead of BST, depending on daylight saving. Times are the same day unless marked.

Kolkata (IST)London, GMT (UTC+0)London, BST (UTC+1)
5:00 AM IST11:30 PM (day before)12:30 AM
5:30 AM IST12:00 AM1:00 AM
6:00 AM IST12:30 AM1:30 AM
6:30 AM IST1:00 AM2:00 AM
7:00 AM IST1:30 AM2:30 AM
7:30 AM IST2:00 AM3:00 AM
8:00 AM IST2:30 AM3:30 AM
8:30 AM IST3:00 AM4:00 AM
9:00 AM IST3:30 AM4:30 AM
9:30 AM IST4:00 AM5:00 AM
10:00 AM IST4:30 AM5:30 AM
10:30 AM IST5:00 AM6:00 AM
11:00 AM IST5:30 AM6:30 AM
11:30 AM IST6:00 AM7:00 AM
12:00 PM IST6:30 AM7:30 AM
12:30 PM IST7:00 AM8:00 AM
1:00 PM IST7:30 AM8:30 AM
1:30 PM IST8:00 AM9:00 AM
2:00 PM IST8:30 AM9:30 AM
2:30 PM IST9:00 AM10:00 AM
3:00 PM IST9:30 AM10:30 AM
3:30 PM IST10:00 AM11:00 AM
4:00 PM IST10:30 AM11:30 AM
4:30 PM IST11:00 AM12:00 PM
5:00 PM IST11:30 AM12:30 PM
5:30 PM IST12:00 PM1:00 PM
6:00 PM IST12:30 PM1:30 PM
6:30 PM IST1:00 PM2:00 PM
7:00 PM IST1:30 PM2:30 PM
7:30 PM IST2:00 PM3:00 PM
8:00 PM IST2:30 PM3:30 PM
8:30 PM IST3:00 PM4:00 PM
9:00 PM IST3:30 PM4:30 PM
9:30 PM IST4:00 PM5:00 PM
10:00 PM IST4:30 PM5:30 PM
10:30 PM IST5:00 PM6:00 PM
11:00 PM IST5:30 PM6:30 PM
11:30 PM IST6:00 PM7:00 PM
The other way

GMT to IST: London working hours

GMT is 5 hours 30 minutes behind IST, or BST is 4 hours 30 minutes behind IST, depending on daylight saving. Times are the same day unless marked.

London timeKolkata, IST, when London is on GMTKolkata, IST, when London is on BST
7:00 AM12:30 PM11:30 AM
8:00 AM1:30 PM12:30 PM
9:00 AM2:30 PM1:30 PM
10:00 AM3:30 PM2:30 PM
11:00 AM4:30 PM3:30 PM
12:00 PM5:30 PM4:30 PM
1:00 PM6:30 PM5:30 PM
2:00 PM7:30 PM6:30 PM
3:00 PM8:30 PM7:30 PM
4:00 PM9:30 PM8:30 PM
5:00 PM10:30 PM9:30 PM
6:00 PM11:30 PM10:30 PM
3-step workflow · a minute

Pick a meeting time in three steps

Add the cities, read the overlap, share the time.

  1. STEP 01

    Add the cities

    Pick where each person is. The first city is the reference for the meeting time.

    Up to 12 cities
  2. STEP 02

    Read the overlap

    The banner shows the hours when every city is between 9:00 and 17:00.

    Live clocks
  3. STEP 03

    Copy or export

    Choose a start time and copy it for every city, or download a PDF.

    Dates included
Guide

How to use the time zone scheduler

Most mix-ups come from daylight saving and from meetings that fall on a different date somewhere else.

Offsets from your browser's time zone data, so summer time is current
  1. 1

    Put yourself first

    Your own city first makes the meeting picker read in your local time.

  2. 2

    Pick cities, not offsets

    A city carries its daylight saving rules. A fixed offset like UTC-5 does not.

  3. 3

    Check the date line

    Each meeting card shows the day too. A morning call in India can be the evening before in the US.

  4. 4

    Save your team

    Your cities are kept in this browser, so the same team is there next time.

Reading the studio

What the colours mean

Each clock, meeting card and hour bar uses the same three states.

9:00 to 17:00

Working hours

Green. A fair time for a work call in that city.

  • Counted in the overlap
  • Shown in green
  • Weekends are not checked
6:00 to 20:00

Daytime

Amber. Awake, but before or after the working day.

  • Early starts
  • Evening calls
  • Ask first
20:00 to 6:00

Night

Grey. Most people are asleep or off work.

  • Avoid if you can
  • Rotate if you must
  • Record instead
Marker

Now

The tall dark block on each 24-hour bar is the current hour there.

  • Moves every hour
  • Clocks tick each second
  • DST tag in summer time
Guide

Who plans across time zones

The same overlap, very different calendars.

IT and services teams

Client calls

Indian teams finding the window when a US or UK client is also at work.

Uses: Kolkata first · add client city

Support teams

Handovers

Seeing which region is in office now, to hand a ticket to the right shift.

Uses: Live clocks · now marker

Students and tutors

Classes

Booking an online class that lands in daytime for both sides.

Uses: Meeting time · date on card

Podcasters and hosts

Guests

Sending a guest their local time and date with the PDF or copied text.

Uses: Copy schedule · PDF
Daylight saving

Why the gap between cities changes

Some places move their clocks for summer, others never do. The studio reads the rules for each city.

Offsets in 2026

15 January, then 15 July:

Kolkata

UTC+5:30 · UTC+5:30

New York

UTC-5 · UTC-4

London

UTC+0 · UTC+1

Sydney

UTC+11 · UTC+10

Tokyo

UTC+9 · UTC+9

The gap moves

New York compared with Kolkata:

  • January: +10:30h ahead in Kolkata
  • July: +9:30h ahead in Kolkata
  • India keeps one offset all year
  • The US moves its clocks twice a year

Every half hour, both ways: IST to EST conversion table.

US dates by law

Under 15 U.S.C. 260a, US daylight saving time runs:

  • From 2 a.m. on the second Sunday of March
  • To 2 a.m. on the first Sunday of November
  • Other countries set their own dates
  • The DST tag shows when a city is on summer time
Guide

Keeping a recurring meeting fair

A weekly call across regions needs a check twice a year.

  1. 1

    Recheck in March and November

    When the US or Europe changes clocks, the overlap can grow or shrink by an hour.

  2. 2

    Rotate the late slot

    If there is no overlap, take turns on who joins early or late.

  3. 3

    Send times with dates

    Copy schedule adds the date for each city, so nobody turns up a day off.

  4. 4

    Keep the team saved

    Up to 12 cities stay in this browser. Save favourites after a change.

Compare

Ways to pick a time across zones

Doing the sums by hand works, until daylight saving changes.

QuestionThis schedulerMental mathsFixed UTC offsets
Handles daylight saving✓ Per city✗ Easy to forget✗ Offsets are fixed
Shows working-hours overlap✓ For all citiesOne pair at a timeBy hand
Shows the local date✓ On each cardOften missedBy hand
Shareable result✓ Text or PDF✗ No✗ No

Want to know what the call costs? Try the Meeting Cost Calculator.

Pro tips

Pro tips for global meetings

Small habits that stop the 3 a.m. invite.

Reference first

The first city sets the meeting time. To change it, Clear all and add your own city first.

Mind the date

A card that says a different day means the meeting crosses midnight there.

Amber is a favour

An amber slot is awake but outside work. Ask before booking it.

Rotate pain

No overlap? Alternate the early and late slots week by week.

Save favourites

Your cities are saved automatically. Save favourites makes sure after big changes.

Paste into the invite

Copy schedule gives one line per city with its date. Paste it into the invite.

PDF for clients

Export PDF makes a one-page schedule that marks working and non-working times.

Travelling?

Add where you will be, not where you live, for the dates you are away.

Pro tip: some pairs barely overlap

With 9:00 to 17:00 working hours on 15 January 2026, Kolkata and London share 3 h, from 2:30 PM Kolkata time. Kolkata and New York share none. When there is none, use an amber slot one side agrees to, rotate it, or record the meeting.

Which one?

City names or UTC offsets?

Both describe a time zone. Only one keeps up with summer time.

Follows the rules
America/New_YorkIANA zone

City zone

Carries the city's daylight saving history and rules, so the offset is right on any date.

UTC-5 in winter · UTC-4 in summer

Fixed
UTC-5offset only

Offset

The same all year. Fine for places without summer time, wrong for half the year elsewhere.

Right for part of the year

Verdict: always pick the city. The studio lists 43 of them so you never have to type an offset.
Use cases

What people schedule with it

Six everyday calls across time zones.

Client calls

India to US or UK, inside both working days.

Team stand-ups

A daily slot that suits every office.

Online classes

A tutor and a student on different continents.

Podcast guests

A guest's local time and date, sent as text.

Shift handovers

Which region is in office right now.

Family calls

A time that is daytime for relatives abroad.

FAQ

Frequently asked questions

Quick answers about time zones, daylight saving and finding a meeting time.

How many hours ahead is IST from UK time?
IST (UTC+5:30) is 5 hours 30 minutes ahead of GMT, the UK's winter time. When the UK is on British Summer Time (BST, UTC+1), IST is 4 hours 30 minutes ahead.
What is 2 PM IST in UK time?
2:00 PM IST is 8:30 AM GMT, or 9:30 AM BST in UK summer. 3:30 PM IST is 10:00 AM GMT (11:00 AM BST).
What is 9 AM IST in GMT?
9:00 AM IST is 3:30 AM GMT, or 4:30 AM BST.
What is 9 AM UK time in IST?
9:00 AM GMT is 2:30 PM IST. 9:00 AM BST is 1:30 PM IST.
When do India and UK working hours overlap?
In GMT season, 2:30 PM to 5 PM IST is 9 AM to 11:30 AM in London. In BST season the overlap is 1:30 PM to 5 PM IST, which is 9 AM to 12:30 PM in the UK.
When does the UK switch between GMT and BST?
BST starts on the last Sunday in March (28 March 2027) and GMT on the last Sunday in October (it switched on 25 October 2026). These dates differ from the US by a few weeks.
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Other versions of this tool, each set up for a specific need.