Offset
The time difference between Iran Standard Time and Mountain Time is 9.5 hours.
Iran Standard Time (IRST) is ahead of Mountain Time (MDT).
IRST: UTC+3:30
MDT: UTC-6
Mountain Time is currently observing daylight saving time; Iran Standard Time is not.
When to schedule
Standard business hours (9 AM–5 PM, Mon–Fri) in Iran Standard Time and Mountain Time don't overlap on the same weekday. Mountain Time is 9 hours behind Iran Standard Time.
With some flexibility, there’s a workable window outside standard hours:
- 5 PM–8 PM in Iran Standard Time (7 AM–10 AM in Mountain Time) — suggest 6:00 PM Iran Standard Time (8:30 AM Mountain Time).
This means an early start or late finish for one side, but it’s a reasonable slot for a one-off meeting.
This window may shift by an hour during daylight saving time.
Public holidays in 2026
National public holidays can affect availability — a counterpart is likely off work on their own holidays, so it's worth planning meetings and deadlines around them.
United States
- New Year's DayThu, Jan 1
- Martin Luther King, Jr. DayMon, Jan 19
- Presidents DayMon, Feb 16
- Memorial DayMon, May 25
- Juneteenth National Independence DayFri, Jun 19
- Independence DayFri, Jul 3
- Labour DayMon, Sep 7
- Columbus DayMon, Oct 12
- Veterans DayWed, Nov 11
- Thanksgiving DayThu, Nov 26
- Christmas DayFri, Dec 25
About these zones
Iran Standard Time is also known as IRST. To call Iran, dial +98.
Mountain Time is also known as MST, or MDT. To call United States, dial +1.
Mountain Time is approximately 7,000 miles north of Iran Standard Time.
Quick reference
Full 24-hour conversion table — tap any time to open it in the converter.
| IRST | MST | Day |
|---|---|---|
| 12:00 am | 2:30 pm | -1 day |
| 1:00 am | 3:30 pm | -1 day |
| 2:00 am | 4:30 pm | -1 day |
| 3:00 am | 5:30 pm | -1 day |
| 4:00 am | 6:30 pm | -1 day |
| 5:00 am | 7:30 pm | -1 day |
| 6:00 am | 8:30 pm | -1 day |
| 7:00 am | 9:30 pm | -1 day |
| 8:00 am | 10:30 pm | -1 day |
| 9:00 am | 11:30 pm | -1 day |
| 10:00 am | 12:30 am | Same day |
| 11:00 am | 1:30 am | Same day |
| 12:00 pm | 2:30 am | Same day |
| 1:00 pm | 3:30 am | Same day |
| 2:00 pm | 4:30 am | Same day |
| 3:00 pm | 5:30 am | Same day |
| 4:00 pm | 6:30 am | Same day |
| 5:00 pm | 7:30 am | Same day |
| 6:00 pm | 8:30 am | Same day |
| 7:00 pm | 9:30 am | Same day |
| 8:00 pm | 10:30 am | Same day |
| 9:00 pm | 11:30 am | Same day |
| 10:00 pm | 12:30 pm | Same day |
| 11:00 pm | 1:30 pm | Same day |
Daylight saving time
Mountain Time observes daylight saving time; Iran Standard Time does not. The offset between the two zones changes when Mountain Time transitions: on Sunday, November 1, 2026, clocks fall back from MDT to MST.
See the daylight saving time page for transition dates across every time zone.
Daylight today
- Sunrise
- 4:50 AM
- Sunset
- 7:18 PM
- Day length
- 14h 28m
- Sunrise
- 5:34 AM
- Sunset
- 8:25 PM
- Day length
- 14h 51m
Daylight overlap: 1h 5m — 4:50 AM–5:55 AM in Iran Standard Time (7:20 PM–8:25 PM in Mountain Time). Both locations are in daylight during this window.
Cities in these zones
Cities in Mountain Time
Browse all cities to see the current local time anywhere.
Airports in these zones
Airports in Iran Standard Time
- IKA
- THR
- MHD
- IFN
- PYK
- TBZ
Airports in Mountain Time
- BJC
- DEN
- OGD
- SLC
Related conversions
Common conversions
- What is 9:00 am IRST in MST?
- 9:00 am IRST is 11:30 pm MST, the previous day.
- What is 12:00 pm IRST in MST?
- 12:00 pm IRST is 2:30 am MST.
- What is 12:30 pm IRST in MST?
- 12:30 pm IRST is 3:00 am MST.
- What is 2:00 pm IRST in MST?
- 2:00 pm IRST is 4:30 am MST.
- What is 5:00 pm IRST in MST?
- 5:00 pm IRST is 7:30 am MST.
- What is 11:30 pm IRST in MST?
- 11:30 pm IRST is 2:00 pm MST.