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HDT
Hawaii Daylight Time
GMT -9
12am
3am
6am
9am
12pm
3pm
6pm
9pm
HDT is not used on this date
This converter keeps HDT at GMT -9. Honolulu uses HST (GMT -10) on this date. Open the HST converter, or choose Honolulu, Pearl City, or Hilo for city-specific time.
HAST
Hawaii-Aleutian Standard Time
GMT -10
12am
3am
6am
9am
12pm
3pm
6pm
9pm

Quick answers

HDT is 1 hour ahead of HAST year-round.

Working hours of 9:00 am to 5:00 pm in HDT correspond to 8:00 am to 4:00 pm in HAST.

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

Time Difference

Hawaii Daylight Time is 1 hour ahead of Hawaii-Aleutian Standard Time
3:00 am03:00 in HDT is 2:00 am02:00 in HAST

HDT to HAST call time
Best time for a conference call or a meeting is between 10am-5pm in HDT which corresponds to 9am-4pm in HAST

3:00 am03:00 Hawaii Daylight Time (HDT). Offset UTC -9:00 hours
2:00 am02:00 Hawaii-Aleutian Standard Time (HAST). Offset UTC -10:00 hours

3:00 am03:00 HDT / 2:00 am02:00 HAST

HDTHAST
12am (midnight)11pm
1am12am (midnight)
2am1am
3am2am
4am3am
5am4am
6am5am
7am6am
8am7am
9am8am
10am9am
11am10am
12pm (noon)11am
1pm12pm (noon)
2pm1pm
3pm2pm
4pm3pm
5pm4pm
6pm5pm
7pm6pm
8pm7pm
9pm8pm
10pm9pm
11pm10pm
00:0023:00
01:0000:00
02:0001:00
03:0002:00
04:0003:00
05:0004:00
06:0005:00
07:0006:00
08:0007:00
09:0008:00
10:0009:00
11:0010:00
12:0011:00
13:0012:00
14:0013:00
15:0014:00
16:0015:00
17:0016:00
18:0017:00
19:0018:00
20:0019:00
21:0020:00
22:0021:00
23:0022:00

Hawaii Daylight Time

Offset: HDT is 9 hours behind Greenwich Mean Time (GMT) and is used in Pacific

Countries using this time zone: United States

HDT 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 west of the zero meridian.
Military/NATO: Used by the U.S. military, Chinese military and others
  • Victor - Military abbreviation for HDT
  • V - short form of 'Victor'
IANA/Olson: Reflects HDT time zone boundaries defined by political bodies, primarily intended for use with computer programs and operating systems
  • America/Adak
  • America/Atka
  • US/Aleutian
Time zones with the GMT -9 offset:
  • AKST - Alaska Standard Time
  • AHDT - Alaska-Hawaii Daylight Time
  • HADT - Hawaii-Aleutian Daylight Time
  • GAMT - Gambier Time
  • HDT - Hawaii Daylight Time
  • V - Victor Time Zone

Hawaii-Aleutian Standard Time

Offset: HAST is 10 hours behind Greenwich Mean Time (GMT) and is used in America

Countries using this time zone: United States

Daylight Saving: This is a standard time zone. During summer, some places set clocks forward one hour for daylight saving time and observe Hawaii-Aleutian Daylight Time (HADT).

Daylight saving time clock moves back for one hour from 2am to 1amStart: Hawaii-Aleutian Standard Time (HAST) 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: Hawaii-Aleutian Standard Time (HAST) 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.

HAST 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 an offset of ten hours to the west of the zero meridian.
Military/NATO: Used by the U.S. military, Chinese military and others
  • Whiskey - Military abbreviation for HAST
  • W - short form of 'Whiskey'
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