Z
Zulu Time Zone
GMT +0
12am
3am
6am
9am
12pm
3pm
6pm
9pm
AST
Atlantic Standard Time
GMT -4
12am
3am
6am
9am
12pm
3pm
6pm
9pm

Quick answers

Z is 4 hours ahead of AST. Z uses GMT +0, and AST uses GMT -4 for this comparison.

For example, 12:00 pm Z is 8:00 am AST. Use the converter above to adjust the date or time and create a shareable meeting link.

Best meeting overlap: 1pm-5pm Z, which is 9am-1pm AST.

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

Time Difference

Zulu Time Zone is 4 hours ahead of Atlantic Standard Time
12:00 pm12:00 in Z is 8:00 am08:00 in AST

Z to AST call time
Best time for a conference call or a meeting is between 1pm-5pm in Z which corresponds to 9am-1pm in AST

12:00 pm12:00 Zulu Time Zone (Z). Offset UTC 0:00 hours
8:00 am08:00 Atlantic Standard Time (AST). Offset UTC -4:00 hours

12:00 pm12:00 Z / 8:00 am08:00 AST

ZAST
12am (midnight)8pm
1am9pm
2am10pm
3am11pm
4am12am (midnight)
5am1am
6am2am
7am3am
8am4am
9am5am
10am6am
11am7am
12pm (noon)8am
1pm9am
2pm10am
3pm11am
4pm12pm (noon)
5pm1pm
6pm2pm
7pm3pm
8pm4pm
9pm5pm
10pm6pm
11pm7pm
00:0020:00
01:0021:00
02:0022:00
03:0023:00
04:0000:00
05:0001:00
06:0002:00
07:0003:00
08:0004:00
09:0005:00
10:0006:00
11:0007:00
12:0008:00
13:0009:00
14:0010:00
15:0011:00
16:0012:00
17:0013:00
18:0014:00
19:0015:00
20:0016:00
21:0017:00
22:0018:00
23:0019:00

Zulu Time Zone

Offset: Z is 0 hours ahead Greenwich Mean Time (GMT) and is used in Military

Coordinated Universal Time (UTC) is the world time standard that regulates clocks and time. It is successor to Greenwich Mean Time (GMT). For casual use, UTC is the same as GMT, but is used by the scientific community.
UTC is the time standard commonly used across the world since 1972. It is used in many technical fields, like aviation industry and meteorologists, also used to synchronize time across internet networks.

Z 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 Z
  • Z - short form of 'Zulu'
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 - Universal Time Coordinated
  • WT - Western Sahara Standard Time
  • Z - Zulu Time Zone

Atlantic Standard Time

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

Countries using this time zone: 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 time zone is Santo Domingo in Dominican Republic, with about 2.202 million people. Other major cities in this time zone include 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. During summer, some places set clocks forward one hour for daylight saving time and observe Atlantic Daylight Time (ADT).

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

Daylight saving time clock moves forward for one hour from 2am to 3amEnd: Atlantic Standard Time (AST) ends on Sunday, March 8, 2026 at 2:00 am local time and clocks are set one hour forward to Sunday, March 8, 2026, 3:00 am local daylight time instead. Standard time ends annually on the second Sunday of March.

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 an offset of four hours 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
  • HLV - Hora Legal de Venezuela
  • PYT - Paraguay Time
  • Q - Quebec Time Zone
  • VET - Venezuelan Standard Time