Tehran to AST
-7h 30mTehran
IRSTSOURCEAST
ASTGreen rows indicate typical business hours (9 AM - 5 PM)
IRST and AST on the World Map
The map below highlights the IRST (Iran Standard Time) and AST (Atlantic Standard Time) timezone regions across the globe.
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.
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.
About Tehran
WikipediaTehran operates on Iran Standard Time (IRST), UTC+3:30. Iran's unique half-hour offset makes Tehran time distinctive for regional business coordination.
Iran Standard Time (IRST) is one of few timezones with a 30-minute offset (UTC+3:30).
Understanding the -7h 30m Gap: Tehran vs AST
Tehran runs on Iran Standard Time (IRST) at UTC+03:30. AST runs on Atlantic Standard Time (AST) at UTC-04:00. That puts Tehran 7 hours 30 minutes behind AST — a difference of -7h 30m at the current offsets.
In practice, when it is 9:00 AM in Tehran it is 1:30 AM in AST. Midnight in Tehran is 4:30 PM in AST. Neither zone observes daylight saving time, so the offset between them stays constant all year.
Tehran to AST time conversion table
| Tehran (IRST) | AST (AST) | Day |
|---|---|---|
| 12:00 AM | 4:30 PM | previous day |
| 6:00 AM | 10:30 PM | previous day |
| 7:00 AM | 11:30 PM | previous day |
| 8:00 AM | 12:30 AM | same day |
| 9:00 AM | 1:30 AM | same day |
| 12:00 PM | 4:30 AM | same day |
| 3:00 PM | 7:30 AM | same day |
| 5:00 PM | 9:30 AM | same day |
| 6:00 PM | 10:30 AM | same day |
| 9:00 PM | 1:30 PM | same day |
Why people convert Tehran to AST time
- Scheduling a call from Tehran to AST: a 10:00 AM start in Tehran lands at 2:30 AM in AST, so you can confirm the slot without doing the arithmetic yourself.
- Finding shared working hours: both Tehran and AST are inside the 9-to-5 working day between 4:30 PM and 5:00 PM IRST time (9:00 AM–9:30 AM AST). That is roughly 0 hours 30 minutes of usable overlap.
- Booking travel or deliveries: tracking AST local time against Tehran keeps pickup windows and arrival estimates honest across the -7h 30m offset.
- Always state the zone abbreviation, not just the hour. "3:00 PM IRST" is unambiguous; "3 PM" across a -7h 30m gap is not.
- Block 4:30 PM–5:00 PM IRST as the recurring meeting window if you work primarily from Tehran and need AST colleagues present.
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.
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 Tehran and AST
Both Tehran and AST sit inside the 9 AM – 5 PM working day between 4:30 PM–5:00 PM IRST, which is 9:00 AM–9:30 AM AST. That gives roughly 0 hours and 30 minutes of shared time — the safest window for a live call or meeting.
Business hours overlap
Tehran and AST overlap for only 30 minutes (4:30 PM–5:00 PM IRST), so meetings have to be booked precisely.
Tehran is 7 hours 30 minutes behind AST (IRST UTC+03:30 → AST UTC-04:00). The shared working window is 4:30 PM–5:00 PM IRST. Remember to re-check around daylight-saving transitions.
🕐 Daylight Saving Time Info
Tehran
Does not observe DST
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 Tehran and AST?
Tehran (IRST, UTC+03:30) is 7 hours 30 minutes behind AST (AST, UTC-04:00). The gap is currently -7h 30m.
How do I convert Tehran time to AST time?
Add -7h 30m to Tehran local time. For example, 9:00 AM in Tehran is 1:30 AM 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 -7h 30m offset from Tehran.
What is the best time to call AST from Tehran?
Call between 4:30 PM and 5:00 PM IRST — that maps to 9:00 AM–9:30 AM AST and keeps both parties inside the working day.
Which is behind, Tehran or AST?
Tehran is 7 hours 30 minutes behind AST. When it is 12:00 PM in Tehran it is 4:30 AM in AST.
Do Tehran and AST use different time zones?
Tehran (Iran) uses IRST at UTC+03:30, while AST uses AST at UTC-04:00. The IANA identifiers are Asia/Tehran and America/Halifax.
Does daylight saving time affect the Tehran–AST difference?
Neither zone observes daylight saving time, so the -7h 30m offset between Tehran and AST is fixed all year.
Which other cities share Tehran's time zone?
IRST also covers Tehran, Isfahan, Mashhad, Tabriz, Shiraz, Karaj.
Which countries use IRST, Tehran's zone?
IRST is used in Iran.
Is there a day difference between Tehran and AST?
Not normally. The -7h 30m gap only pushes the date over the previous day.
What is the time difference between Tehran and AST?
AST is -7h 30m from Tehran.
What timezone is Tehran in?
Tehran operates on Iran Standard Time (IRST), UTC+3:30. Iran's unique half-hour offset makes Tehran time distinctive for regional business coordination.
What timezone is AST in?
AST operates on its local timezone.
What are the business hours in Tehran?
Standard business hours in Tehran are 8:00 AM - 4:00 PM IRST.
Which countries use IRST (Iran Standard Time)?
IRST is used in Iran.
Does IRST observe daylight saving time?
Yes, IRST switches to IRDT during summer months.
What are some interesting facts about IRST?
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).
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 Tehran, what time is it in AST?
When it is 12:00 AM (midnight) in Tehran (IRST), it is -7h 30m later in AST (AST).
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