IST
India Standard Time
GMT +5:30
AST
Atlantic Standard Time
GMT -4
AST is NOT in use by many locations
ADT (Atlantic Daylight Time) is used instead. Switch to ADT time zone or select one of the cities Santo Domingo, Santiago de los Caballeros, Santo Domingo Oeste for automatic timezone change.

Time Difference

India Standard Time is 9 hours and 30 minutes ahead of Atlantic Standard Time
So 12:30 am00:30 in IST is 3:00 pm15:00 in AST

12:30 am00:30 India Standard Time (IST). Offset UTC +5:30 hours
3:00 pm15:00 Atlantic Standard Time (AST). Offset UTC -4:00 hours

12:30 am00:30 IST / 3:00 pm15:00 AST

IST AST
12am (midnight) 2:30 pm
1am 3:30 pm
2am 4:30 pm
3am 5:30 pm
4am 6:30 pm
5am 7:30 pm
6am 8:30 pm
7am 9:30 pm
8am 10:30 pm
9am 11:30 pm
10am 12:30 am
11am 1:30 am
12pm (noon) 2:30 am
1pm 3:30 am
2pm 4:30 am
3pm 5:30 am
4pm 6:30 am
5pm 7:30 am
6pm 8:30 am
7pm 9:30 am
8pm 10:30 am
9pm 11:30 am
10pm 12:30 pm
11pm 1:30 pm
0:00 14:30
1:00 15:30
2:00 16:30
3:00 17:30
4:00 18:30
5:00 19:30
6:00 20:30
7:00 21:30
8:00 22:30
9:00 23:30
10:00 0:30
11:00 1:30
12:00 2:30
13:00 3:30
14:00 4:30
15:00 5:30
16:00 6:30
17:00 7:30
18:00 8:30
19:00 9:30
20:00 10:30
21:00 11:30
22:00 12:30
23:00 13:30

India Standard Time

Offset: IST is 5 hours and 30 minutes ahead Greenwich Mean Time (GMT) and is used in Asia

Countries: It is used in following countries: India

Principal Cities: The largest city in the IST timezone is Mumbai from India with population about 12.692 million people. Other major cities in the area are Delhi, Bangalore, Kolkata, Chennai

Daylight Saving: India Standard Time (IST) is not adjusted for daylight saving therefore IST remains the same through out the year. This means, unlike some time zones where the clock is set forward by one hour every summer and backward by one hour during winter to adjust for daylight saving, India Standard Time remains the same

IST Time Zone Geo Map
IST timezone map
IST representations, usage and related time zones

W3C/ISO-8601: International standard covering representation and exchange of dates and time-related data
  • +0530 - basic
  • +05:30 - extended

Email/RFC-2822: Internet Message Format Date Standard, typically used for timestamps in email headers
  • +0530 - sign character (+) followed by a four digit time providing hours (05) and minutes (30) of the offset. Indicates five hour and thirty minutes time differences to the east of the zero meridian.

IANA/Olson: Reflects IST time zone boundaries defined by political bodies, primarily intended for use with computer programs and operating systems
  • Asia/Calcutta
  • Asia/Kolkata

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


Atlantic Standard Time

Offset: AST is 4 hours behind Greenwich Mean Time (GMT) and is used in North America

Countries: It is used in following countries: Antigua & Barbuda, Anguilla, Aruba, Barbados, St Barthelemy, Bermuda, Caribbean NL, Canada, Curaçao, Dominica, Dominican Republic, Grenada, Greenland, Guadeloupe, St Kitts & Nevis, St Lucia, St Martin (French), Martinique, Montserrat, Puerto Rico, St Maarten (Dutch), Trinidad & Tobago, St Vincent, Virgin Islands (UK), Virgin Islands (US)

Principal Cities: The largest city in the AST timezone is Santo Domingo from Dominican Republic with population about 2.202 million people. Other major cities in the area are Santiago de los Caballeros, Santo Domingo Oeste, San Juan, Halifax

Daylight Saving: This is a standard timezone, however during summer some places adjust time for one hour forward for daylight saving and observe Atlantic Daylight Time (ADT).

End: AST ends annually on the same date and time. and clocks were set one hour forward on Sunday, March 10, 2019, at 2:00 (2:00 am) local time.

Start: AST starts annually on the same date and time. and clocks are set one hour back on Sunday, November 3, 2019, at 2:00 (2:00 am) local time.

French: HNA - Heure Normale de l'Atlantique

Spanish: AST - Tiempo Estándar del Atlántico

AST Time Zone Geo Map
AST timezone map
AST representations, usage and related time zones

W3C/ISO-8601: International standard covering representation and exchange of dates and time-related data
  • -04 - basic short
  • -0400 - basic
  • -04:00 - extended

Email/RFC-2822: Internet Message Format Date Standard, typically used for timestamps in email headers
  • -0400 - sign character (-) followed by a four digit time providing hours (04) and minutes (00) of the offset. Indicates four hour and zero minutes time differences to the west of the zero meridian.

Military/NATO: Used by the U.S. military, Chinese military and others
  • Quebec - Military abbreviation for AST
  • Q - short form of 'Quebec'

IANA/Olson: Reflects AST time zone boundaries defined by political bodies, primarily intended for use with computer programs and operating systems
  • America/Anguilla
  • America/Antigua
  • America/Aruba
  • America/Barbados
  • America/Blanc-Sablon
  • America/Curacao
  • America/Dominica
  • America/Glace_Bay
  • America/Goose_Bay
  • America/Grenada
  • America/Guadeloupe
  • America/Halifax
  • America/Kralendijk
  • America/Lower_Princes
  • America/Marigot
  • America/Martinique
  • America/Moncton
  • America/Montserrat
  • America/Port_of_Spain
  • America/Puerto_Rico
  • America/Santo_Domingo
  • America/St_Barthelemy
  • America/St_Kitts
  • America/St_Lucia
  • America/St_Thomas
  • America/St_Vincent
  • America/Thule
  • America/Tortola
  • America/Virgin
  • Atlantic/Bermuda
  • Canada/Atlantic

AST Abbreviation: Several time zones share AST abbreviation and it could refer to these time zones

  • Atlantic Standard Time - UTC -4
  • Arabia Standard Time - UTC +3

Time zones with the GMT -4 offset:

  • AST - Atlantic Standard Time
  • EDT - Eastern Daylight Time
  • AMT - Amazon Time
  • BOT - Bolivia Time
  • CDT - Cuba Daylight Time
  • CLT - Chile Standard Time
  • FKT - Falkland Island Time
  • GYT - Guyana Time
  • PYT - Paraguay Time
  • Q - Quebec Time Zone
  • VET - Venezuelan Standard Time
  • -04 -