|

KST to AST Converter

KST
Korea Standard Time
GMT +9
12am
3am
6am
9am
12pm
3pm
6pm
9pm
AST
Atlantic Standard Time
GMT -4
12am
3am
6am
9am
12pm
3pm
6pm
9pm

Quick answers

KST is 13 hours ahead of AST. KST uses GMT +9, and AST uses GMT -4 for this comparison.

For example, 9:00 pm KST is 8:00 am AST. Use the converter above to adjust the date or time and create a shareable meeting link.

Best meeting overlap: 7am-8am KST, which is 6pm-7pm AST (previous day).

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

Time Difference

Korea Standard Time is 13 hours ahead of Atlantic Standard Time
9:00 pm21:00 in KST is 8:00 am08:00 in AST

KST to AST call time
Best time for a conference call or a meeting is between 7am-8am in KST which corresponds to 6pm-7pm in AST (previous day)

9:00 pm21:00 Korea Standard Time (KST). Offset UTC +9:00 hours
8:00 am08:00 Atlantic Standard Time (AST). Offset UTC -4:00 hours

9:00 pm21:00 KST / 8:00 am08:00 AST

KSTAST
12am (midnight)11am
1am12pm (noon)
2am1pm
3am2pm
4am3pm
5am4pm
6am5pm
7am6pm
8am7pm
9am8pm
10am9pm
11am10pm
12pm (noon)11pm
1pm12am (midnight)
2pm1am
3pm2am
4pm3am
5pm4am
6pm5am
7pm6am
8pm7am
9pm8am
10pm9am
11pm10am
00:0011:00
01:0012:00
02:0013:00
03:0014:00
04:0015:00
05:0016:00
06:0017:00
07:0018:00
08:0019:00
09:0020:00
10:0021:00
11:0022:00
12:0023:00
13:0000:00
14:0001:00
15:0002:00
16:0003:00
17:0004:00
18:0005:00
19:0006:00
20:0007:00
21:0008:00
22:0009:00
23:0010:00

Korea Standard Time

Offset: KST is 9 hours ahead Greenwich Mean Time (GMT) and is used in Asia

Countries using this time zone: Korea (North), Korea (South)

Principal Cities: The largest city in the KST time zone is Seoul in South Korea, with about 10.349 million people. Other major cities in this time zone include Busan, Pyongyang, Incheon, Daegu.

Daylight Saving: Clocks in Korea Standard Time (KST) do not change for daylight saving time, so KST stays the same throughout the year. Other time zones may set clocks forward in summer and back in winter.

KST Time Zone Geo Map
KST timezone map

KST representations, usage and related time zones

W3C/ISO-8601: International standard covering representation and exchange of dates and time-related data
  • +09 - basic short
  • +0900 - basic
  • +09:00 - extended
Email/RFC-2822: Internet Message Format Date Standard, typically used for timestamps in email headers
  • +0900 - sign character (+) followed by a four digit time providing hours (09) and minutes (00) of the offset. Indicates an offset of nine hours to the east of the zero meridian.
Military/NATO: Used by the U.S. military, Chinese military and others
  • India - Military abbreviation for KST
  • I - short form of 'India'
IANA/Olson: Reflects KST time zone boundaries defined by political bodies, primarily intended for use with computer programs and operating systems
  • Asia/Pyongyang
  • Asia/Seoul
  • ROK
KST Abbreviation: Several time zones share KST abbreviation and it could refer to these time zones
  • Korea Standard Time - UTC +9
  • Pyongyang Time - UTC +8:30
Time zones with the GMT +9 offset:
  • AWDT - Australian Western Daylight Time
  • CHOST - Choibalsan Summer Time
  • I - India Time Zone
  • IRKST - Irkutsk Summer Time
  • JST - Japan Standard Time
  • KST - Korea Standard Time
  • PWT - Palau Time
  • TLT - East Timor Time
  • ULAST - Ulaanbaatar Summer Time
  • WIT - Eastern Indonesian Time
  • YAKT - Yakutsk Time

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
EST to ISTGMT to ESTPST to ESTEST to GMTPST to GMT