PST to AST Time Converter
AST is 4 hours ahead of PST. The US West Coast is currently on PDT (UTC-7:00), and Atlantic Canada and the Caribbean are currently on ADT (UTC-3:00).
Best Time to Call Between PST and AST
Both zones are inside normal business hours between 9:00 AM and 1:00 PM PST — that's 1:00 PM to 5:00 PM AST. That's a 4-hour window.
both at work PST only AST only neither — hours along the strip are PST.
Common Times Converted
PST on the left, AST on the right.
PST to AST: Full 24-Hour Conversion Table
Shaded rows are working hours; the darker shade marks the hours when both zones are at work.
| PST | AST | Working hours |
|---|---|---|
| 12:00 AM | 4:00 AM | — |
| 1:00 AM | 5:00 AM | — |
| 2:00 AM | 6:00 AM | — |
| 3:00 AM | 7:00 AM | — |
| 4:00 AM | 8:00 AM | — |
| 5:00 AM | 9:00 AM | AST only |
| 6:00 AM | 10:00 AM | AST only |
| 7:00 AM | 11:00 AM | AST only |
| 8:00 AM | 12:00 PM | AST only |
| 9:00 AM | 1:00 PM | Both zones |
| 10:00 AM | 2:00 PM | Both zones |
| 11:00 AM | 3:00 PM | Both zones |
| 12:00 PM | 4:00 PM | Both zones |
| 1:00 PM | 5:00 PM | PST only |
| 2:00 PM | 6:00 PM | PST only |
| 3:00 PM | 7:00 PM | PST only |
| 4:00 PM | 8:00 PM | PST only |
| 5:00 PM | 9:00 PM | — |
| 6:00 PM | 10:00 PM | — |
| 7:00 PM | 11:00 PM | — |
| 8:00 PM | 12:00 AM next day | — |
| 9:00 PM | 1:00 AM next day | — |
| 10:00 PM | 2:00 AM next day | — |
| 11:00 PM | 3:00 AM next day | — |
What PST and AST Actually Are
PST — Pacific Standard Time
Los Angeles, San Francisco, Seattle, Las Vegas, Vancouver. Standing at UTC-8:00 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 PST. The Philippines occasionally uses PST for Philippine Standard Time (UTC+8); PHT is the clearer label for that.
California voted in 2018 to move to permanent daylight time, but the change needs an act of Congress and has never happened, so PST is still the winter standard.
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
Both sides change clocks, on different dates
Both regions observe daylight saving but do not switch on the same day, so for a week or two each spring and fall the gap between them is an hour different from the rest of the year. Those short windows are where recurring invitations quietly break.
Major Cities in Each Zone
Cities on PST
Cities on AST
Frequently Asked Questions
What is the time difference between PST and AST?
AST is 4 hours ahead of PST.
What is 9:00 AM PST in AST?
9:00 AM PST is 1:00 PM AST.
What are the best hours to schedule a call between PST and AST?
Between 9:00 AM and 1:00 PM PST, which is 1:00 PM to 5:00 PM AST. Both sides are inside normal business hours through that window.
Does the difference between PST and AST change during the year?
Yes. Both regions observe daylight saving, and they do not switch on the same dates, so the gap shifts by an hour at least twice a year. The next clock change is on Sunday, November 1, 2026.
Does PST always mean Pacific Standard Time?
The Philippines occasionally uses PST for Philippine Standard Time (UTC+8); PHT is the clearer label for that.
Does AST always mean Atlantic Standard Time?
AST also stands for Arabia Standard Time (UTC+3), used in Saudi Arabia, Iraq and Kuwait.