HST
Hawaii Standard Time
GMT -10
ADT
Atlantic Daylight Time
GMT -3

Time Difference

Hawaii Standard Time is 7 hours behind Atlantic Daylight Time
2:30 pm14:30 in HST is 9:30 pm21:30 in ADT

HST to ADT call time
Best time for a conference call or a meeting is between 8am-11am in HST which corresponds to 3pm-6pm in ADT

2:30 pm14:30 Hawaii Standard Time (HST). Offset UTC -10:00 hours
9:30 pm21:30 Atlantic Daylight Time (ADT). Offset UTC -3:00 hours

2:30 pm14:30 HST / 9:30 pm21:30 ADT

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

Hawaii Standard Time

Offset: HST is 10 hours behind Greenwich Mean Time (GMT) and is used in Pacific

Countries: It is used in following countries: United States

Principal Cities: The largest city in the HST timezone is Honolulu from USA with population about 371,657 people. Other major cities in the area are Pearl City, Hilo, Kailua, Waipahu

Daylight Saving: Hawaii Standard Time (HST) is not adjusted for daylight saving therefore HST 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, Hawaii Standard Time remains the same

HST Time Zone Geo Map
HST timezone map

HST representations, usage and related time zones

W3C/ISO-8601: International standard covering representation and exchange of dates and time-related data
  • -10 - basic short
  • -1000 - basic
  • -10:00 - extended
Email/RFC-2822: Internet Message Format Date Standard, typically used for timestamps in email headers
  • -1000 - sign character (-) followed by a four digit time providing hours (10) and minutes (00) of the offset. Indicates ten 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
  • Whiskey - Military abbreviation for HST
  • W - short form of 'Whiskey'
IANA/Olson: Reflects HST time zone boundaries defined by political bodies, primarily intended for use with computer programs and operating systems
  • America/Adak
  • America/Atka
  • HST
  • Pacific/Honolulu
  • Pacific/Johnston
  • US/Aleutian
  • US/Hawaii
Time zones with the GMT -10 offset:
  • HAST - Hawaii-Aleutian Standard Time
  • CKT - Cook Island Time
  • HST - Hawaii Standard Time
  • TAHT - Tahiti Time
  • W - Whiskey Time Zone

Atlantic Daylight Time

Offset: ADT is 3 hours behind Greenwich Mean Time (GMT) and is used in North America

Countries: It is used in following countries: Bermuda, Canada, Greenland

Principal Cities: The largest city in the ADT timezone is Halifax from Canada with population about 359,111 people. Other major cities in the area are Sydney, Dartmouth, Saint John, Moncton

French: HAA - Heure Avancée de l'Atlantique

ADT Time Zone Geo Map
ADT timezone map

Daylight Saving: Atlantic Daylight Time (ADT) is a daylight saving/summer timezone, however during winter some places switch clocks for one hour back and observe Atlantic Standard Time (AST).

Daylight saving time clock moves forward for one hour from 2am to 3amStart: Atlantic Daylight Time (ADT) started 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. Daylight saving starts annually the on second Sunday of March

Daylight saving time clock moves back for one hour from 2am to 1amEnd: Atlantic Daylight Time (ADT) ends 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 local standard time instead. Daylight saving ends annually the on first Sunday of November

ADT representations, usage and related time zones

W3C/ISO-8601: International standard covering representation and exchange of dates and time-related data
  • -03 - basic short
  • -0300 - basic
  • -03:00 - extended
Email/RFC-2822: Internet Message Format Date Standard, typically used for timestamps in email headers
  • -0300 - sign character (-) followed by a four digit time providing hours (03) and minutes (00) of the offset. Indicates three 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
  • Papa - Military abbreviation for ADT
  • P - short form of 'Papa'
IANA/Olson: Reflects ADT time zone boundaries defined by political bodies, primarily intended for use with computer programs and operating systems
  • America/Glace_Bay
  • America/Goose_Bay
  • America/Halifax
  • America/Moncton
  • America/Thule
  • Atlantic/Bermuda
  • Canada/Atlantic
Time zones with the GMT -3 offset:
  • ADT - Atlantic Daylight Time
  • PMT - Pierre & Miquelon Standard Time
  • PMST - Pierre & Miquelon Standard Time
  • WGT - West Greenland Time
  • AMST - Amazon Summer Time
  • ART - Argentina Time
  • BRT - Brasília time
  • CLST - Chile Summer Time
  • FKST - Falkland Islands Summer Time
  • GFT - French Guiana Time
  • P - Papa Time Zone
  • PYST - Paraguay Summer Time
  • SRT - Suriname Time
  • UYT - Uruguay Time