HST to AST Time Converter
AST is 7 hours ahead of HST. HST is UTC-10:00, and Atlantic Canada and the Caribbean are currently on ADT (UTC-3:00).
Best Time to Call Between HST and AST
Both zones are inside normal business hours between 9:00 AM and 10:00 AM HST — that's 4:00 PM to 5:00 PM AST. That's a 1-hour window.
both at work HST only AST only neither — hours along the strip are HST.
Common Times Converted
HST on the left, AST on the right.
HST to AST: Full 24-Hour Conversion Table
Shaded rows are working hours; the darker shade marks the hours when both zones are at work.
| HST | AST | Working hours |
|---|---|---|
| 12:00 AM | 7:00 AM | — |
| 1:00 AM | 8:00 AM | — |
| 2:00 AM | 9:00 AM | AST only |
| 3:00 AM | 10:00 AM | AST only |
| 4:00 AM | 11:00 AM | AST only |
| 5:00 AM | 12:00 PM | AST only |
| 6:00 AM | 1:00 PM | AST only |
| 7:00 AM | 2:00 PM | AST only |
| 8:00 AM | 3:00 PM | AST only |
| 9:00 AM | 4:00 PM | Both zones |
| 10:00 AM | 5:00 PM | HST only |
| 11:00 AM | 6:00 PM | HST only |
| 12:00 PM | 7:00 PM | HST only |
| 1:00 PM | 8:00 PM | HST only |
| 2:00 PM | 9:00 PM | HST only |
| 3:00 PM | 10:00 PM | HST only |
| 4:00 PM | 11:00 PM | HST only |
| 5:00 PM | 12:00 AM next day | — |
| 6:00 PM | 1:00 AM next day | — |
| 7:00 PM | 2:00 AM next day | — |
| 8:00 PM | 3:00 AM next day | — |
| 9:00 PM | 4:00 AM next day | — |
| 10:00 PM | 5:00 AM next day | — |
| 11:00 PM | 6:00 AM next day | — |
What HST and AST Actually Are
HST — Hawaii Standard Time
Honolulu and the rest of Hawaii. Standing at UTC-10:00 as written, and the region does not change its clocks, so that offset holds all year. Hawaii does not observe daylight saving, so this offset holds all year.
Hawaii dropped daylight saving in 1967 and never resumed it. Being close to the equator, its daylight barely varies across the year, so there is little to gain.
AST — Atlantic Standard Time
Halifax, San Juan, Santo Domingo, Bermuda. Standing at UTC-4:00 as written, and the region does change its clocks, so its live offset moves by an hour twice a year. The next change is on Sunday, November 1, 2026, to AST. AST also stands for Arabia Standard Time (UTC+3), used in Saudi Arabia, Iraq and Kuwait.
Atlantic Standard Time is the only North American zone whose name is more commonly associated, worldwide, with a completely different zone — Arabia Standard Time.
What This Means in Practice
This gap is not fixed
AST changes its clocks and HST does not, so the difference between them moves by an hour twice a year. A recurring meeting set now will drift for one side from Sunday, November 1, 2026 unless someone resets it.
Major Cities in Each Zone
Cities on HST
Cities on AST
Frequently Asked Questions
What is the time difference between HST and AST?
AST is 7 hours ahead of HST. That is the live figure. Taken strictly as written, the gap between HST and AST is 6 hours — the two differ because at least one of these regions is currently on daylight saving.
What is 9:00 AM HST in AST?
9:00 AM HST is 4:00 PM AST.
What are the best hours to schedule a call between HST and AST?
Between 9:00 AM and 10:00 AM HST, which is 4:00 PM to 5:00 PM AST. Both sides are inside normal business hours through that window.
Does the difference between HST and AST change during the year?
Yes. AST observes daylight saving and HST does not, so the gap shifts by an hour at least twice a year. The next clock change is on Sunday, November 1, 2026.
Does HST always mean Hawaii Standard Time?
Hawaii does not observe daylight saving, so this offset holds all year.
Does AST always mean Atlantic Standard Time?
AST also stands for Arabia Standard Time (UTC+3), used in Saudi Arabia, Iraq and Kuwait.