PST to AST
+4hPST
PSTSOURCEAST
ASTGreen rows indicate typical business hours (9 AM - 5 PM)
PST and AST on the World Map
The map below highlights the PST (Pacific Standard Time) and AST (Atlantic Standard Time) timezone regions across the globe.
PST – Pacific Standard Time
UTC-08:00Pacific Standard Time (PST) is the time zone for the US and Canadian Pacific coast, 8 hours behind UTC.
- •Silicon Valley and the world's biggest tech companies operate on Pacific Time.
- •The Hollywood film industry runs on PST/PDT.
- •PST is 3 hours behind EST, creating a significant business hours gap.
- •Vancouver, Canada's third-largest city, uses PST.
AST – Atlantic Standard Time
UTC-04:00Atlantic Standard Time (AST) is the time zone for the Canadian Atlantic provinces and the Caribbean, 4 hours behind UTC.
- •Puerto Rico uses AST year-round and does not observe DST.
- •AST is 1 hour ahead of EST.
- •Halifax, the capital of Nova Scotia, is the largest city in AST Canada.
Everything You Need to Know About PST and AST Time
PST runs on Pacific Standard Time (PST) at UTC-08:00. AST runs on Atlantic Standard Time (AST) at UTC-04:00. That puts PST 4 hours ahead of AST — a difference of +4h at the current offsets.
In practice, when it is 9:00 AM in PST it is 1:00 PM in AST. Midnight in PST is 4:00 AM in AST. Neither zone observes daylight saving time, so the offset between them stays constant all year.
PST to AST time conversion table
| PST (PST) | AST (AST) | Day |
|---|---|---|
| 12:00 AM | 4:00 AM | same day |
| 6:00 AM | 10:00 AM | same day |
| 7:00 AM | 11:00 AM | same day |
| 8:00 AM | 12:00 PM | same day |
| 9:00 AM | 1:00 PM | same day |
| 12:00 PM | 4:00 PM | same day |
| 3:00 PM | 7:00 PM | same day |
| 5:00 PM | 9:00 PM | same day |
| 6:00 PM | 10:00 PM | same day |
| 9:00 PM | 1:00 AM | next day |
Why people convert PST to AST time
- Scheduling a call from PST to AST: a 10:00 AM start in PST lands at 2:00 PM in AST, so you can confirm the slot without doing the arithmetic yourself.
- Finding shared working hours: both PST and AST are inside the 9-to-5 working day between 9:00 AM and 1:00 PM PST time (1:00 PM–5:00 PM AST). That is roughly 4 hours of usable overlap.
- Watching a live event or market open: PST viewers need 1:00 PM in AST to catch a 9:00 AM start there, and 8:00 PM if the event is anchored to PST.
- Always state the zone abbreviation, not just the hour. "3:00 PM PST" is unambiguous; "3 PM" across a +4h gap is not.
- Block 9:00 AM–1:00 PM PST as the recurring meeting window if you work primarily from PST and need AST colleagues present.
About PST (Pacific Standard Time)
Pacific Standard Time (PST) covers the west coast of North America, including tech hubs like San Francisco and Seattle, and entertainment capital Los Angeles. The Pacific Time Zone is home to Silicon Valley and the world's largest technology companies. During summer, clocks advance to Pacific Daylight Time (PDT, UTC-07:00). PST is also observed in Baja California, Mexico.
About AST (Atlantic Standard Time)
Atlantic Standard Time (AST) covers Canada's Atlantic provinces (Nova Scotia, New Brunswick, Prince Edward Island, and most of Labrador), as well as several Caribbean nations. Puerto Rico and the US Virgin Islands use AST year-round without daylight saving time. The Canadian provinces switch to Atlantic Daylight Time (ADT) in summer.
Best time to call between PST and AST
Both PST and AST sit inside the 9 AM – 5 PM working day between 9:00 AM–1:00 PM PST, which is 1:00 PM–5:00 PM AST. That gives roughly 4 hours of shared time — the safest window for a live call or meeting.
Business hours overlap
PST and AST overlap for about 4 hours during the working day — enough for meetings if you avoid the edges of the window.
PST is 4 hours ahead of AST (PST UTC-08:00 → AST UTC-04:00). The shared working window is 9:00 AM–1:00 PM PST. Remember to re-check around daylight-saving transitions.
🕐 Daylight Saving Time Info
PST
☀ Currently in DST
Standard: UTC-08:00 · DST: UTC-07:00
Clocks fall back on Sun, Nov 1, 2026
AST
☀ Currently in DST
Standard: UTC-04:00 · DST: UTC-03:00
Clocks fall back on Sun, Nov 1, 2026
Learn More About Time
Dive deeper into the fascinating world of timekeeping, time zones, and how they shape our global society:
Frequently Asked Questions
What is the time difference between PST and AST?
PST (PST, UTC-08:00) is 4 hours ahead of AST (AST, UTC-04:00). The gap is currently +4h.
How do I convert PST time to AST time?
Add +4h to PST local time. For example, 9:00 AM in PST is 1:00 PM in AST.
What time is it in AST right now?
AST uses AST at UTC-04:00. Use the live converter at the top of this page — it updates in real time and already accounts for the +4h offset from PST.
What is the best time to call AST from PST?
Call between 9:00 AM and 1:00 PM PST — that maps to 1:00 PM–5:00 PM AST and keeps both parties inside the working day.
Which is ahead, PST or AST?
PST is 4 hours ahead of AST. When it is 12:00 PM in PST it is 4:00 PM in AST.
Does daylight saving time affect the PST–AST difference?
Neither zone observes daylight saving time, so the +4h offset between PST and AST is fixed all year.
Which other cities share PST's time zone?
PST also covers Los Angeles, San Francisco, Seattle, Vancouver, San Diego, Portland, Las Vegas, Sacramento and 2 more.
Which countries use PST, PST's zone?
PST is used in United States (Pacific), Canada (British Columbia), Mexico (Baja California).
Is there a day difference between PST and AST?
Not normally. The +4h gap only pushes the date over for late-evening times.
What is the time difference between PST and AST?
AST is +4h from PST.
What timezone is PST in?
PST operates on its local timezone.
What timezone is AST in?
AST operates on its local timezone.
Which countries use PST (Pacific Standard Time)?
PST is used in United States (Pacific), Canada (British Columbia), Mexico (Baja California).
Does PST observe daylight saving time?
Yes, PST switches to PDT during summer months.
What are some interesting facts about PST?
Silicon Valley and the world's biggest tech companies operate on Pacific Time. The Hollywood film industry runs on PST/PDT.
Which cities are in the AST timezone?
Major cities in the AST timezone include Halifax, San Juan, Santo Domingo, Caracas, La Paz, Fredericton, Charlottetown.
What is the UTC offset for AST?
Atlantic Standard Time (AST) is at UTC-04:00. During daylight saving time, it shifts to ADT.
What should I know about the AST timezone?
Puerto Rico uses AST year-round and does not observe DST. AST is 1 hour ahead of EST.
When is it midnight in PST, what time is it in AST?
When it is 12:00 AM (midnight) in PST (PST), it is +4h later in AST (AST).
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See every conversion from PST →·See every conversion from AST →