CDT to Tehran
+8h 30mCDT
CDTSOURCETehran
IRSTGreen rows indicate typical business hours (9 AM - 5 PM)
CDT and IRST on the World Map
The map below highlights the CDT (Central Daylight Time) and IRST (Iran Standard Time) timezone regions across the globe.
CDT – Central Daylight Time
UTC-05:00Central Daylight Time (CDT) is the daylight saving offset in the Central Time Zone, 5 hours behind UTC.
- •CDT is the same offset as EST (UTC-05:00), which can cause confusion.
- •CDT runs from the second Sunday in March to the first Sunday in November.
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.
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).
Everything You Need to Know About CDT and Tehran Time
CDT runs on Central Daylight Time (CDT) at UTC-05:00. Tehran runs on Iran Standard Time (IRST) at UTC+03:30. That puts CDT 8 hours 30 minutes ahead of Tehran — a difference of +8h 30m at the current offsets.
In practice, when it is 9:00 AM in CDT it is 5:30 PM in Tehran. Midnight in CDT is 8:30 AM in Tehran. Neither zone observes daylight saving time, so the offset between them stays constant all year.
CDT to Tehran time conversion table
| CDT (CDT) | Tehran (IRST) | Day |
|---|---|---|
| 12:00 AM | 8:30 AM | same day |
| 6:00 AM | 2:30 PM | same day |
| 7:00 AM | 3:30 PM | same day |
| 8:00 AM | 4:30 PM | same day |
| 9:00 AM | 5:30 PM | same day |
| 12:00 PM | 8:30 PM | same day |
| 3:00 PM | 11:30 PM | same day |
| 5:00 PM | 1:30 AM | next day |
| 6:00 PM | 2:30 AM | next day |
| 9:00 PM | 5:30 AM | next day |
Why people convert CDT to Tehran time
- Scheduling a call from CDT to Tehran: a 10:00 AM start in CDT lands at 6:30 PM in Tehran, so you can confirm the slot without doing the arithmetic yourself.
- Handling a +8h 30m gap: CDT and Tehran have no overlap inside a normal 9-to-5 day, so real-time meetings need an early-morning or late-evening slot on one side. 9:00 AM in Tehran is 5:30 PM in CDT.
- Watching a live event or market open: CDT viewers need 5:30 PM in Tehran to catch a 9:00 AM start there, and 3:30 PM if the event is anchored to CDT.
- Always state the zone abbreviation, not just the hour. "3:00 PM CDT" is unambiguous; "3 PM" across a +8h 30m gap is not.
- With a +8h 30m gap there is no shared 9-to-5 window, so alternate the early start: one week CDT takes the early slot, the next week Tehran does.
About CDT (Central Daylight Time)
Central Daylight Time (CDT) is observed during summer months in the US and Canadian portions of the Central Time Zone. Clocks are moved forward by one hour, aligning with Eastern Standard Time (EST). Most of Mexico and Central America do not observe CDT, staying on CST year-round.
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 CDT and Tehran
With a +8h 30m offset there is no overlap inside a normal 9 AM – 5 PM day. Tehran opens at 9:00 AM IRST, which is 5:30 PM in CDT, so real-time calls need an early-morning or late-evening slot on one side.
Business hours overlap
CDT and Tehran have no shared working hours because of the +8h 30m gap. Teams need to alternate early starts or rely on asynchronous handovers.
CDT is 8 hours 30 minutes ahead of Tehran (CDT UTC-05:00 → IRST UTC+03:30). There is no shared 9-to-5 window, so plan around an early or late slot. Remember to re-check around daylight-saving transitions.
🕐 Daylight Saving Time Info
CDT
☀ Currently in DST
Standard: UTC-06:00 · DST: UTC-05:00
Clocks fall back on Sun, Nov 1, 2026
Tehran
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 CDT and Tehran?
CDT (CDT, UTC-05:00) is 8 hours 30 minutes ahead of Tehran (IRST, UTC+03:30). The gap is currently +8h 30m.
How do I convert CDT time to Tehran time?
Add +8h 30m to CDT local time. For example, 9:00 AM in CDT is 5:30 PM in Tehran.
What time is it in Tehran right now?
Tehran 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 +8h 30m offset from CDT.
What is the best time to call Tehran from CDT?
There is no shared working-hours window because of the +8h 30m gap. The closest option is 1:00 PM in CDT, which is 9:30 PM in Tehran.
Which is ahead, CDT or Tehran?
CDT is 8 hours 30 minutes ahead of Tehran. When it is 12:00 PM in CDT it is 8:30 PM in Tehran.
Do CDT and Tehran use different time zones?
CDT uses CDT at UTC-05:00, while Tehran (Iran) uses IRST at UTC+03:30. The IANA identifiers are America/Chicago and Asia/Tehran.
Does daylight saving time affect the CDT–Tehran difference?
Neither zone observes daylight saving time, so the +8h 30m offset between CDT and Tehran is fixed all year.
Which other cities share CDT's time zone?
CDT also covers Chicago, Houston, Dallas, Austin, Winnipeg, Nashville.
Which countries use CDT, CDT's zone?
CDT is used in United States (Central), Canada (Manitoba).
Is there a day difference between CDT and Tehran?
Not normally. The +8h 30m gap only pushes the date over for late-evening times.
What is the time difference between CDT and Tehran?
Tehran is +8h 30m from CDT.
What timezone is CDT in?
CDT operates on its local timezone.
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 are the business hours in Tehran?
Standard business hours in Tehran are 8:00 AM - 4:00 PM IRST.
Which countries use CDT (Central Daylight Time)?
CDT is used in United States (Central), Canada (Manitoba).
Does CDT observe daylight saving time?
Yes, CDT switches to CST during summer months.
What are some interesting facts about CDT?
CDT is the same offset as EST (UTC-05:00), which can cause confusion. CDT runs from the second Sunday in March to the first Sunday in November.
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 CDT, what time is it in Tehran?
When it is 12:00 AM (midnight) in CDT (CDT), it is +8h 30m later in Tehran (IRST).
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