Tehran to Denver
-9h 30mTehran
IRSTSOURCEDenver
MDTGreen rows indicate typical business hours (9 AM - 5 PM)
IRST and MDT on the World Map
The map below highlights the IRST (Iran Standard Time) and MDT (Mountain 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.
MST – Mountain Standard Time
UTC-07:00Mountain Standard Time (MST) is the time zone for the Mountain region of North America, 7 hours behind UTC.
- •Arizona does not observe daylight saving time, staying on MST year-round.
- •The Navajo Nation in Arizona does observe DST, unlike the rest of the state.
- •Denver, the 'Mile High City', is the largest city fully in MST.
- •MST covers 6 US states entirely and parts of several others.
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).
About Denver
WikipediaDenver operates on Mountain Time (MST/MDT), 2 hours behind New York. As a tech and aerospace hub, Denver bridges West Coast and Central US business hours.
Denver International Airport is the largest airport in North America by land area.
Tehran vs Denver: Offsets, DST and Best Call Times
Tehran runs on Iran Standard Time (IRST) at UTC+03:30. Denver runs on Mountain Daylight Time (MDT) at UTC-06:00, also currently on daylight saving time. That puts Tehran 9 hours 30 minutes behind Denver — a difference of -9h 30m at the current offsets.
In practice, when it is 9:00 AM in Tehran it is 11:30 PM in Denver on the previous day. Midnight in Tehran is 2:30 PM in Denver.Denver observes daylight saving time while Tehran does not, so the gap narrows or widens by an hour part of the year.
Tehran to Denver time conversion table
| Tehran (IRST) | Denver (MDT) | Day |
|---|---|---|
| 12:00 AM | 2:30 PM | previous day |
| 6:00 AM | 8:30 PM | previous day |
| 7:00 AM | 9:30 PM | previous day |
| 8:00 AM | 10:30 PM | previous day |
| 9:00 AM | 11:30 PM | previous day |
| 12:00 PM | 2:30 AM | same day |
| 3:00 PM | 5:30 AM | same day |
| 5:00 PM | 7:30 AM | same day |
| 6:00 PM | 8:30 AM | same day |
| 9:00 PM | 11:30 AM | same day |
Why people convert Tehran to Denver time
- Scheduling a call from Tehran to Denver: a 10:00 AM start in Tehran lands at 12:30 AM in Denver, so you can confirm the slot without doing the arithmetic yourself.
- Handling a -9h 30m gap: Tehran and Denver 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 Denver is 11:30 PM in Tehran.
- Watching a live event or market open: Tehran viewers need 11:30 PM in Denver to catch a 9:00 AM start there, and 9:30 AM if the event is anchored to Tehran.
- Always state the zone abbreviation, not just the hour. "3:00 PM IRST" is unambiguous; "3 PM" across a -9h 30m gap is not.
- With a -9h 30m gap there is no shared 9-to-5 window, so alternate the early start: one week Tehran takes the early slot, the next week Denver does.
- Denver: Clocks fall back on Sun, Nov 1, 2026. Any meeting series spanning that date will shift by an hour in local time.
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 MST (Mountain Standard Time)
Mountain Standard Time (MST) covers the Rocky Mountain region of the United States and Canada. Arizona is notable for not observing daylight saving time, staying on MST year-round (except the Navajo Nation). The time zone includes major cities like Denver, Phoenix, Calgary, and Salt Lake City. During summer, most areas switch to Mountain Daylight Time (MDT, UTC-06:00).
Best time to call between Tehran and Denver
With a -9h 30m offset there is no overlap inside a normal 9 AM – 5 PM day. Denver opens at 9:00 AM MDT, which is 11:30 PM in Tehran, so real-time calls need an early-morning or late-evening slot on one side.
Business hours overlap
Tehran and Denver have no shared working hours because of the -9h 30m gap. Teams need to alternate early starts or rely on asynchronous handovers.
Tehran is 9 hours 30 minutes behind Denver (IRST UTC+03:30 → MDT UTC-06:00). 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
Tehran
Does not observe DST
Denver
☀ Currently in DST
Standard: UTC-07:00 · DST: UTC-06:00
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 Denver?
Tehran (IRST, UTC+03:30) is 9 hours 30 minutes behind Denver (MDT, UTC-06:00). The gap is currently -9h 30m.
How do I convert Tehran time to Denver time?
Add -9h 30m to Tehran local time. For example, 9:00 AM in Tehran is 11:30 PM in Denver (previous day).
What time is it in Denver right now?
Denver uses MDT at UTC-06:00. Use the live converter at the top of this page — it updates in real time and already accounts for the -9h 30m offset from Tehran.
What is the best time to call Denver from Tehran?
There is no shared working-hours window because of the -9h 30m gap. The closest option is 1:00 PM in Tehran, which is 3:30 AM in Denver.
Which is behind, Tehran or Denver?
Tehran is 9 hours 30 minutes behind Denver. When it is 12:00 PM in Tehran it is 2:30 AM in Denver.
Do Tehran and Denver use different time zones?
Tehran (Iran) uses IRST at UTC+03:30, while Denver (USA) uses MDT at UTC-06:00. The IANA identifiers are Asia/Tehran and America/Denver.
Does daylight saving time affect the Tehran–Denver difference?
Yes at the moment: Denver is on daylight saving time and Tehran is not, so the -9h 30m gap shifts by an hour when exactly one of them changes clocks.
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 Denver?
Not normally. The -9h 30m gap only pushes the date over the previous day.
What is the time difference between Tehran and Denver?
Denver is -9h 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 Denver in?
Denver operates on Mountain Time (MST/MDT), 2 hours behind New York. As a tech and aerospace hub, Denver bridges West Coast and Central US business hours.
What are the business hours in Tehran?
Standard business hours in Tehran are 8:00 AM - 4:00 PM IRST.
What are the business hours in Denver?
Standard business hours in Denver are 8:00 AM - 5:00 PM MST.
What is the best time to schedule a call between Tehran and Denver?
The best overlap for a call is when both cities are in business hours. Tehran works 8:00 AM - 4:00 PM IRST and Denver works 8:00 AM - 5:00 PM MST (-9h 30m difference). Try scheduling during the overlapping window for maximum convenience.
What currencies are used in Tehran and Denver?
Tehran uses IRR (﷼) while Denver uses USD ($). Check current exchange rates when planning travel or business between these cities.
How do Tehran and Denver compare in size?
Tehran has a population of approximately 9.4 million (metro: 16.8 million), while Denver has approximately 715,000 (metro: 2.9 million).
What are the major landmarks in Tehran and Denver?
Tehran is known for Azadi Tower, Golestan Palace, Grand Bazaar. Denver is famous for Red Rocks Amphitheatre, Denver Art Museum, Union Station.
Do Tehran and Denver have stock exchanges?
Yes. Tehran has the TSE (Tehran Stock Exchange) and Denver has the N/A (Uses NYSE/NASDAQ). The -9h 30m time difference affects trading hour overlaps between these exchanges.
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 MST timezone?
Major cities in the MST timezone include Denver, Phoenix, Salt Lake City, Calgary, Edmonton, Albuquerque, El Paso, Tucson.
What is the UTC offset for MST?
Mountain Standard Time (MST) is at UTC-07:00. During daylight saving time, it shifts to MDT.
What should I know about the MST timezone?
Arizona does not observe daylight saving time, staying on MST year-round. The Navajo Nation in Arizona does observe DST, unlike the rest of the state.
When is it midnight in Tehran, what time is it in Denver?
When it is 12:00 AM (midnight) in Tehran (IRST), it is -9h 30m later in Denver (MST).
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