AST to IRST
+7h 30mAST
ASTSOURCEIRST
IRSTGreen rows indicate typical business hours (9 AM - 5 PM)
AST and IRST on the World Map
The map below highlights the AST (Atlantic Standard Time) and IRST (Iran Standard Time) timezone regions across the globe.
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.
IRST – Iran Standard Time
UTC+03:30Iran Standard Time (IRST) is the time zone for Iran, 3 hours and 30 minutes ahead of UTC.
- •IRST is one of only a few time zones with a 30-minute offset.
- •Iran observes daylight saving time, switching to IRDT (UTC+04:30).
- •Tehran has a metropolitan population of over 16 million.
Time Conversion Guide: AST to IRST
AST runs on Atlantic Standard Time (AST) at UTC-04:00. IRST runs on Iran Standard Time (IRST) at UTC+03:30. That puts AST 7 hours 30 minutes ahead of IRST — a difference of +7h 30m at the current offsets.
In practice, when it is 9:00 AM in AST it is 4:30 PM in IRST. Midnight in AST is 7:30 AM in IRST. Neither zone observes daylight saving time, so the offset between them stays constant all year.
AST to IRST time conversion table
| AST (AST) | IRST (IRST) | Day |
|---|---|---|
| 12:00 AM | 7:30 AM | same day |
| 6:00 AM | 1:30 PM | same day |
| 7:00 AM | 2:30 PM | same day |
| 8:00 AM | 3:30 PM | same day |
| 9:00 AM | 4:30 PM | same day |
| 12:00 PM | 7:30 PM | same day |
| 3:00 PM | 10:30 PM | same day |
| 5:00 PM | 12:30 AM | next day |
| 6:00 PM | 1:30 AM | next day |
| 9:00 PM | 4:30 AM | next day |
Why people convert AST to IRST time
- Scheduling a call from AST to IRST: a 10:00 AM start in AST lands at 5:30 PM in IRST, so you can confirm the slot without doing the arithmetic yourself.
- Finding shared working hours: both AST and IRST are inside the 9-to-5 working day between 9:00 AM and 9:30 AM AST time (4:30 PM–5:00 PM IRST). That is roughly 0 hours 30 minutes of usable overlap.
- Coordinating a AST-based team with IRST contacts: quoting times in the other side's local clock — not your own — removes the single biggest source of missed meetings.
- Always state the zone abbreviation, not just the hour. "3:00 PM AST" is unambiguous; "3 PM" across a +7h 30m gap is not.
- Block 9:00 AM–9:30 AM AST as the recurring meeting window if you work primarily from AST and need IRST colleagues present.
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.
About IRST (Iran Standard Time)
Iran Standard Time (IRST) is one of the few time zones with a 30-minute offset. Iran observes daylight saving time (IRDT, UTC+04:30) from late March to late September. Tehran, the capital, is one of the largest cities in the Middle East.
Best time to call between AST and IRST
Both AST and IRST sit inside the 9 AM – 5 PM working day between 9:00 AM–9:30 AM AST, which is 4:30 PM–5:00 PM IRST. That gives roughly 0 hours and 30 minutes of shared time — the safest window for a live call or meeting.
Business hours overlap
AST and IRST overlap for only 30 minutes (9:00 AM–9:30 AM AST), so meetings have to be booked precisely.
AST is 7 hours 30 minutes ahead of IRST (AST UTC-04:00 → IRST UTC+03:30). The shared working window is 9:00 AM–9:30 AM AST. Remember to re-check around daylight-saving transitions.
🕐 Daylight Saving Time Info
AST
☀ Currently in DST
Standard: UTC-04:00 · DST: UTC-03:00
Clocks fall back on Sun, Nov 1, 2026
IRST
Does not observe DST
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 AST and IRST?
AST (AST, UTC-04:00) is 7 hours 30 minutes ahead of IRST (IRST, UTC+03:30). The gap is currently +7h 30m.
How do I convert AST time to IRST time?
Add +7h 30m to AST local time. For example, 9:00 AM in AST is 4:30 PM in IRST.
What time is it in IRST right now?
IRST uses IRST at UTC+03:30. Use the live converter at the top of this page — it updates in real time and already accounts for the +7h 30m offset from AST.
What is the best time to call IRST from AST?
Call between 9:00 AM and 9:30 AM AST — that maps to 4:30 PM–5:00 PM IRST and keeps both parties inside the working day.
Which is ahead, AST or IRST?
AST is 7 hours 30 minutes ahead of IRST. When it is 12:00 PM in AST it is 7:30 PM in IRST.
Does daylight saving time affect the AST–IRST difference?
Neither zone observes daylight saving time, so the +7h 30m offset between AST and IRST is fixed all year.
Which other cities share AST's time zone?
AST also covers Halifax, San Juan, Santo Domingo, Caracas, La Paz, Fredericton, Charlottetown.
Which countries use AST, AST's zone?
AST is used in Canada (Atlantic provinces), Puerto Rico, US Virgin Islands, Dominican Republic, Venezuela, Bolivia, Barbados, Trinidad and Tobago.
Is there a day difference between AST and IRST?
Not normally. The +7h 30m gap only pushes the date over for late-evening times.
What is the time difference between AST and IRST?
IRST is +7h 30m from AST.
What timezone is AST in?
AST operates on its local timezone.
What timezone is IRST in?
IRST operates on its local timezone.
Which countries use AST (Atlantic Standard Time)?
AST is used in Canada (Atlantic provinces), Puerto Rico, US Virgin Islands, Dominican Republic, Venezuela, Bolivia, and 2 more countries.
Does AST observe daylight saving time?
Yes, AST switches to ADT during summer months.
What are some interesting facts about AST?
Puerto Rico uses AST year-round and does not observe DST. AST is 1 hour ahead of EST.
Which cities are in the IRST timezone?
Major cities in the IRST timezone include Tehran, Isfahan, Mashhad, Tabriz, Shiraz, Karaj.
What is the UTC offset for IRST?
Iran Standard Time (IRST) is at UTC+03:30. During daylight saving time, it shifts to IRDT.
What should I know about the IRST timezone?
IRST is one of only a few time zones with a 30-minute offset. Iran observes daylight saving time, switching to IRDT (UTC+04:30).
When is it midnight in AST, what time is it in IRST?
When it is 12:00 AM (midnight) in AST (AST), it is +7h 30m later in IRST (IRST).
Related Developer Tools
Explore more tools that work great with timezone conversions for international teams:
Related Timezone Conversions
More AST time conversions
- ast to halifax
- ast to new york
- ast to london
- ast to dubai
- ast to tokyo
- ast to singapore
- ast to sydney
- ast to los angeles
- ast to paris
- ast to delhi
- ast to mumbai
- ast to berlin
- ast to hong kong
- ast to toronto
- ast to kathmandu
- new york to ast
- london to ast
- dubai to ast
- tokyo to ast
- singapore to ast
- sydney to ast
- los angeles to ast
- paris to ast
- delhi to ast
- mumbai to ast
- berlin to ast
- hong kong to ast
- toronto to ast
- kathmandu to ast
See every conversion from AST →·See every conversion from IRST →