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GMT
UTC+0
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The United Kingdom is on summer time: BST (UTC+1) until Sun, Oct 25.

Iceland and Ghana stay on GMT (UTC+0).

Quick answers

Selected conversion

1:00 pm13:00 IST (UTC+1), Oct 18, 2026 = 12:00 pm12:00 GMT (UTC+0), Oct 18, 2026

IST is 1 hour ahead of GMT.

IST and GMT examples

These examples always use IST (UTC+1) and GMT (UTC+0). They stay the same when you change the date or time above. The selected conversion may differ when daylight saving time applies.

IST is 1 hour ahead of GMT.

How the time difference changes

For most of the year, IST Europe is 1 hour ahead of GMT. From Oct 25, 2026 to Mar 28, 2027, GMT Europe and GMT have the same time.

For most of the year, working hours of 9:00 am to 6:00 pm in IST Europe correspond to 8:00 am to 5:00 pm in GMT. At other times of the year, working hours of 9:00 am to 6:00 pm in GMT Europe correspond to 9:00 am to 6:00 pm in GMT.For most of the year, working hours of 09:00 to 18:00 in IST Europe correspond to 08:00 to 17:00 in GMT. At other times of the year, working hours of 09:00 to 18:00 in GMT Europe correspond to 09:00 to 18:00 in GMT.

Compare IST time with GMT time, including current local time, UTC offsets, time difference, daylight saving changes, working hours, and shareable meeting times.

Time Difference

Irish Standard Time is 1 hour ahead of Greenwich Mean Time.
1:00 pm13:00 in IST is 12:00 pm12:00 in GMT

IST to GMT call time
Best time for a conference call or a meeting is between 10am-6pm10:00-18:00 in IST which corresponds to 9am-5pm09:00-17:00 in GMT

1:00 pm13:00 Irish Standard Time (IST). Offset UTC +1:00 hour
12:00 pm12:00 Greenwich Mean Time (GMT). Offset UTC 0:00 hours

1:00 pm13:00 IST / 12:00 pm12:00 GMT

Choose an hour to update the converter. Day labels such as “next day” or “+1” are relative to the selected date in the first column. Use Up and Down arrow keys, Home or End to move between hours, then Enter or Space to select.

Hourly time comparison
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Irish Standard Time

Offset: IST is 1 hour ahead of Greenwich Mean Time (GMT).

Countries using this time zone: Ireland

Principal Cities: The largest city in the IST time zone is Dublin in Ireland, with about 1.024 million people. Other major cities in this time zone include Cork, Limerick, Galway, Waterford.

Current time in Ireland: Ireland time now

Map of the areas on Irish Standard Time (IST)
IST part of the year

Today all shaded areas are on IST.

Daylight Saving: Irish Standard Time (IST) is a daylight saving/summer time zone. During winter, some places set clocks back one hour and observe Greenwich Mean Time (GMT).

123456789101112Start: Irish Standard Time (IST) started on Sunday, March 29, 2026 at 1:00 am01:00 local time and clocks were set one hour forward to Sunday, March 29, 2026, 2:00 am02:00. Daylight saving starts annually on the last Sunday of March.

123456789101112End: Irish Standard Time (IST) ends on Sunday, October 25, 2026 at 2:00 am02:00 local time and clocks are set one hour back to Sunday, October 25, 2026, 1:00 am01:00 local standard time instead. Daylight saving ends annually on the last Sunday of October.

See Ireland daylight saving time and upcoming clock changes worldwide.

IST representations, usage and related time zones

W3C/ISO-8601: International standard covering representation and exchange of dates and time-related data
  • +01 - basic short
  • +0100 - basic
  • +01:00 - extended
Email/RFC-2822: Internet Message Format Date Standard, typically used for timestamps in email headers
  • +0100 - sign character (+) followed by a four digit time providing hours (01) and minutes (00) of the offset. Indicates an offset of one hour to the east of the zero meridian.
Military/NATO: Used by the U.S. military, Chinese military and others
  • Alpha - Military abbreviation for IST
  • A - short form of 'Alpha'
IANA/Olson: Reflects IST time zone boundaries defined by political bodies, primarily intended for use with computer programs and operating systems
  • Eire
  • Europe/Dublin
IST Abbreviation: Several time zones share IST abbreviation and it could refer to these time zones
  • India Standard Time - UTC +5:30
  • Irish Standard Time - UTC +1
  • Israel Standard Time - UTC +2
Time zones with the GMT +1 offset:
  • BST - British Summer Time
  • CET - Central European Time
  • IST - Irish Standard Time
  • WEST - Western European Summer Time
  • A - Alpha Time Zone
  • CET - Central European Time
  • MEZ - Mitteleuropäische Zeit
  • WAT - West Africa Time
  • WST - Western Sahara Summer Time
  • BMT - Biel Mean Time

Greenwich Mean Time

Offset: GMT is the same as Greenwich Mean Time (GMT).

Countries using this time zone: Antarctica, Burkina Faso, Gambia, Ghana, Greenland, Guernsey, Guinea, Guinea-Bissau, Iceland, Ireland, Isle of Man, Ivory Coast, Jersey, Liberia, Mali, Mauritania, Morocco, Saint Helena, São Tomé and Príncipe, Senegal, Sierra Leone, Togo, United Kingdom, Western Sahara

Principal Cities: The largest city in the GMT time zone is London in the United Kingdom, with about 8.962 million people. Other major cities in this time zone include Abidjan, Bamako, Casablanca, Dakar.

Greenwich Mean Time (GMT) originally referred to the mean solar time at the Royal Observatory in Greenwich, London. It is now often used to refer to Coordinated Universal Time (UTC) when this is viewed as a time zone, and in casual use the two are the same. In the military, GMT is known as Zulu time. Greenwich Mean Time was the same as Universal Time (UT), a standard astronomical concept used in many technical fields, until the introduction of UTC in 1972.

Map of the areas on Greenwich Mean Time (GMT)
GMT all year GMT part of the year

Today the lighter areas are on UTC+1 (British Summer Time, Irish Standard Time).

GMT representations, usage and related time zones

W3C/ISO-8601: International standard covering representation and exchange of dates and time-related data
  • Z - is the zone designator for the zero UTC/GMT offset, also known as 'Zulu' time
  • +00 - basic short
  • +0000 - basic
  • +00:00 - extended
Email/RFC-2822: Internet Message Format Date Standard, typically used for timestamps in email headers
  • +0000 - sign character (+) followed by a four digit time providing hours (00) and minutes (00) of the offset. Indicates the zero UTC/GMT offset.
Military/NATO: Used by the U.S. military, Chinese military and others
  • Zulu - Military abbreviation for GMT
  • Z - short form of 'Zulu'
IANA/Olson: Reflects GMT time zone boundaries defined by political bodies, primarily intended for use with computer programs and operating systems
  • Africa/Abidjan
  • Africa/Accra
  • Africa/Bamako
  • Africa/Banjul
  • Africa/Bissau
  • Africa/Conakry
  • Africa/Dakar
  • Africa/Freetown
  • Africa/Lome
  • Africa/Monrovia
  • Africa/Nouakchott
  • Africa/Ouagadougou
  • Africa/Sao_Tome
  • Africa/Timbuktu
  • America/Danmarkshavn
  • Atlantic/Reykjavik
  • Atlantic/St_Helena
  • Eire
  • Etc/GMT
  • Etc/GMT+0
  • Etc/GMT-0
  • Etc/GMT0
  • Etc/Greenwich
  • Europe/Belfast
  • Europe/Dublin
  • Europe/Guernsey
  • Europe/Isle_of_Man
  • Europe/Jersey
  • Europe/London
  • GB
  • GB-Eire
  • GMT
  • GMT+0
  • GMT-0
  • GMT0
  • Greenwich
  • Iceland
Time zones with the GMT +0 offset:
  • EGST - Eastern Greenland Summer Time
  • GMT - Greenwich Mean Time
  • WET - Western European Time
  • AZOST - Azores Summer Time
  • UTC - Coordinated Universal Time
  • WT - Western Sahara Standard Time
  • Z - Zulu Time Zone