GST
Gulf Standard Time
GMT +4
ADT/AST
Atlantic Daylight Time
GMT -3
AST automatically adjusted to ADT time zone, that is in use

Time Difference

Gulf Standard Time is 7 hours ahead of Atlantic Daylight Time
12:30 pm12:30 in GST is 5:30 am05:30 in ADT

GST to AST call time
Best time for a conference call or a meeting is between 4pm-6pm in GST which corresponds to 8am-10am in AST

12:30 pm12:30 Gulf Standard Time (GST). Offset UTC +4:00 hours
5:30 am05:30 Atlantic Daylight Time (ADT). Offset UTC -3:00 hours

12:30 pm12:30 GST / 5:30 am05:30 ADT

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

Gulf Standard Time

Offset: GST is 4 hours ahead Greenwich Mean Time (GMT) and is used in Asia

GST Time Zone Geo Map
GST timezone map

GST 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 east of the zero meridian.
Military/NATO: Used by the U.S. military, Chinese military and others
  • Delta - Military abbreviation for GST
  • D - short form of 'Delta'
GST Abbreviation: Several time zones share GST abbreviation and it could refer to these time zones
  • Gulf Standard Time - UTC +4
  • Georgia Standard Time - UTC +4
Time zones with the GMT +4 offset:
  • KUYT - Kuybyshev Time
  • MSD - Moscow Daylight Time
  • SAMT - Samara Time
  • AMT - Armenia Time
  • AZT - Azerbaijan Time
  • D - Delta Time Zone
  • GET - Georgia Standard Time
  • GST - Gulf Standard Time
  • MUT - Mauritius Time
  • RET - Reunion Time
  • SCT - Seychelles Time

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

French: HNA - Heure Normale de l'Atlantique

Spanish: AST - Tiempo Estándar del Atlántico

AST Time Zone Geo Map
AST timezone map

Daylight Saving: This is a standard time zone, however during summer some places switch clocks for one hour forward when daylight saving comes into effect and observe Atlantic Daylight Time (ADT).

Daylight saving time clock moves forward for one hour from 2am to 3amEnd: Atlantic Standard Time (AST) has ended on Sunday, March 9, 2025 at 2:00 am local time and clocks were set one hour forward to Sunday, March 9, 2025, 3:00 am local daylight time instead. Standard time ends annually the on second Sunday of March.

Daylight saving time clock moves back for one hour from 2am to 1amStart: Atlantic Standard Time (AST) starts on Sunday, November 2, 2025 at 2:00 am local time and clocks are set one hour back to Sunday, November 2, 2025, 1:00 am. Standard time starts annually the on first Sunday of November.

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
  • Azerbaijan Standard Time - UTC +4
  • Argentina Standard Time - UTC -3
  • Azores Summer Time - UTC +0
  • Apia Standard Time - UTC +13
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
  • HLV - Hora Legal de Venezuela
  • PYT - Paraguay Time
  • Q - Quebec Time Zone
  • VET - Venezuelan Standard Time