AST
Atlantic Standard Time
GMT -4
12am
3am
6am
9am
12pm
3pm
6pm
9pm
United Kingdom
GMT
12am
3am
6am
9am
12pm
3pm
6pm
9pm

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

Time Difference

Atlantic Standard Time is 4 hours behind GMT (Greenwich Mean Time)
8:00 am08:00 in AST is 12:00 pm12:00 in London, United Kingdom

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

8:00 am08:00 Atlantic Standard Time (AST). Offset UTC -4:00 hours
12:00 pm12:00 GMT (Greenwich Mean Time) (London, United Kingdom). Offset UTC 0:00 hours

8:00 am08:00 AST / 12:00 pm12:00 London, United Kingdom

ASTLondon, United Kingdom
12am (midnight)4am
1am5am
2am6am
3am7am
4am8am
5am9am
6am10am
7am11am
8am12pm (noon)
9am1pm
10am2pm
11am3pm
12pm (noon)4pm
1pm5pm
2pm6pm
3pm7pm
4pm8pm
5pm9pm
6pm10pm
7pm11pm
8pm12am (midnight)
9pm1am
10pm2am
11pm3am
00:0004:00
01:0005:00
02:0006:00
03:0007:00
04:0008:00
05:0009:00
06:0010:00
07:0011:00
08:0012:00
09:0013:00
10:0014:00
11:0015:00
12:0016:00
13:0017:00
14:0018:00
15:0019:00
16:0020:00
17:0021:00
18:0022:00
19:0023:00
20:0000:00
21:0001:00
22:0002:00
23:0003:00

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

London Information

Time Zone

Abbreviation / Name
BST - British Summer Time
GMT - Greenwich Mean Time
UTC / GMT Offset
+1:00 hours during British Summer Time, currently in use.
+0:00 hours during Greenwich Mean Time.
Daylight Saving Time Change
+1:00 hour - DST is in use
Daylight Saving Time Starts
Daylight saving time clock moves forward for one hour from 1am to 2amSunday, March 29, 2026 at 1:00 am local time. DST starts annually on the last Sunday of March. Clocks are turned forward 1 hour to Sunday, March 29, 2026 at 2:00 am local daylight time instead. Also called Spring Forward or Summer Time.
Daylight Saving Time Ends
Daylight saving time clock moves back for one hour from 2am to 1amSunday, October 25, 2026 at 2:00 am local time. DST ends annually on the last Sunday of October. Clocks are turned backward 1 hour to Sunday, October 25, 2026 at 1:00 am local standard time instead. Also called Fall Back or switch to Winter Time.

London Facts

Country
United Kingdom
Alternative Names
ILondon, LON, Lakana, Landan, Landen, Ljondan, Llundain, Lodoni, Londain, Londan, Londar, Londe, Londen, Londin, Londinium, Londino, Londn, London, London osh, Londona, Londonas, Londoni, Londono, Londons, Londonu, Londra, Londres, Londrez, Londri, Londro, Londye, Londyn, Londýn, Lonn, Lontoo, Loundres, Luan GJon, Lun-tun, Lunden, Lundra, Lundun, Lundunir, Lundúnir, Lung-dung, Lunnainn, Lunnin, Lunnon, Luân Đôn, Lùn-tûn, Lùng-dŭng, Lûn-tun, Lākana, Lůndůn, Lọndọnu, Ranana, Rānana, ilantan, ladana, landan, landana, leondeon, lndn, london, londoni, lun dui, lun dun, lwndwn, lxndxn, rondon, Łondra, Λονδίνο, Лондан, Лондон, Лондон ош, Лондонъ, Лёндан, Լոնդոն, לאנדאן, לונדון, لأندأن, لندن, لوندون, لەندەن, ܠܘܢܕܘܢ, लंडन, लंदन, लण्डन, लन्डन्, लन्दन, লন্ডন, ਲੰਡਨ, લંડન, ଲଣ୍ଡନ, இலண்டன், లండన్, ಲಂಡನ್, ലണ്ടൻ, ලන්ඩන්, ลอนดอน, ລອນດອນ, ལོན་ཊོན།, လန်ဒန်မြို့, ლონდონი, ለንደን, ᎫᎴ ᏗᏍᎪᏂᎯᏱ, ロンドン, 伦敦, 倫敦, 런던
Population
7,556,900
Currency
Pound (GBP)
Geographic Coordinates
51° 30' N Latitude / 0° 07' W Longitude
International Dialing Code
+44