Does it account for Daylight Saving Time?

Yes, our converter uses the IANA timezone database, which includes all current DST rules for every timezone in the world.

UTC (Coordinated Universal Time) is the primary time standard by which the world regulates clocks. All timezones are defined as offsets from UTC.

Can I compare multiple timezones at once?

Yes, you can add multiple cities or timezones and see the equivalent times side by side.

How many timezones are there in the world?

There are 38 distinct UTC offsets in use, ranging from UTC-12 to UTC+14. This includes half-hour (UTC+5:30 India, UTC+9:30 Australia) and 45-minute offsets (UTC+5:45 Nepal, UTC+8:45 Australia).

What is the International Date Line?

The International Date Line (IDL) runs roughly along the 180° meridian in the Pacific Ocean. When you cross it westward, you gain a day; crossing eastward, you lose a day.

Why do some timezones have 30 or 45 minute offsets?

Countries chose offsets that best matched their solar noon. India uses UTC+5:30 and Nepal uses UTC+5:45 because standard hourly offsets didn't align well with their geography.

Which country has the most timezones?

France has the most (12 timezones) due to overseas territories. Russia spans 11 timezones. The US has 6 (including Hawaii and Alaska).

IRST to MDT

-9h 30m

IRST

IRSTSOURCE

UTC+03:30

HH12

MM00

12:00 (24-hr)

12 AM6 AM12 PM6 PM12 AM

MDT

UTC-06:00☀ DST active

HH02

MM30

02:30 (24-hr)

12 AM6 AM12 PM6 PM12 AM

Quick Reference

Time Conversion Table

IRST

MDT

12:00 AM

2:30 PM-1

2:00 AM

4:30 PM-1

4:00 AM

6:30 PM-1

6:00 AM

8:30 PM-1

8:00 AM

10:30 PM-1

10:00 AM

12:30 AM

12:00 PM

2:30 AM

2:00 PM

4:30 AM

4:00 PM

6:30 AM

6:00 PM

8:30 AM

8:00 PM

10:30 AM

10:00 PM

12:30 PM

Green 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 Daylight Time) timezone regions across the globe.

IRST Zone

→

MDT Zone

Explore all world timezones interactively →

IRST – Iran Standard Time

UTC+03:30

Iran Standard Time (IRST) is the time zone for Iran, 3 hours and 30 minutes ahead of UTC.

Countries in IRST

Iran

Major Cities in IRST

TehranIsfahanMashhadTabrizShirazKaraj

Key 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).
•Tehran has a metropolitan population of over 16 million.

Daylight Saving:Yes – switches to IRDT

Learn more about IRST on Wikipedia

MDT – Mountain Daylight Time

UTC-06:00

Mountain Daylight Time (MDT) is the daylight saving offset in the Mountain Time Zone, 6 hours behind UTC.

Countries in MDT

United States (Mountain)Canada (Alberta)

Major Cities in MDT

DenverCalgaryEdmontonSalt Lake CityBoise

Key Facts about MDT

•MDT shares the same offset as CST (UTC-06:00).
•Arizona does not switch to MDT, remaining on MST.

Daylight Saving:Yes – switches to MST

Learn more about MDT on Wikipedia

IRST to MDT Time Difference – Complete Guide

IRST runs on Iran Standard Time (IRST) at UTC+03:30. MDT runs on Mountain Daylight Time (MDT) at UTC-06:00. That puts IRST 9 hours 30 minutes behind MDT — a difference of -9h 30m at the current offsets.

In practice, when it is 9:00 AM in IRST it is 11:30 PM in MDT on the previous day. Midnight in IRST is 2:30 PM in MDT. Neither zone observes daylight saving time, so the offset between them stays constant all year.

IRST to MDT time conversion table

IRST (IRST)	MDT (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 IRST to MDT time

Scheduling a call from IRST to MDT: a 10:00 AM start in IRST lands at 12:30 AM in MDT, so you can confirm the slot without doing the arithmetic yourself.
Handling a -9h 30m gap: IRST and MDT 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 MDT is 11:30 PM in IRST.
Booking travel or deliveries: tracking MDT local time against IRST keeps pickup windows and arrival estimates honest across the -9h 30m offset.

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 IRST takes the early slot, the next week MDT does.

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 MDT (Mountain Daylight Time)

Mountain Daylight Time (MDT) is observed during summer months in the Mountain Time Zone, except in Arizona which stays on MST year-round. MDT aligns with Central Standard Time (CST) at UTC-06:00.

Best time to call between IRST and MDT

With a -9h 30m offset there is no overlap inside a normal 9 AM – 5 PM day. MDT opens at 9:00 AM MDT, which is 11:30 PM in IRST, so real-time calls need an early-morning or late-evening slot on one side.

Business hours overlap

IRST and MDT have no shared working hours because of the -9h 30m gap. Teams need to alternate early starts or rely on asynchronous handovers.

IRST is 9 hours 30 minutes behind MDT (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

IRST

Does not observe DST

MDT

☀ 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:

⏳

History of Timekeeping

From sundials to atomic clocks - 5000 years of measuring time

🌍

How Time Zones Work

UTC, offsets, and why zones don't follow straight lines

☀️

Daylight Saving Time

DST dates, which countries observe it, and the ongoing debate

Frequently Asked Questions

What is the time difference between IRST and MDT?

IRST (IRST, UTC+03:30) is 9 hours 30 minutes behind MDT (MDT, UTC-06:00). The gap is currently -9h 30m.

How do I convert IRST time to MDT time?

Add -9h 30m to IRST local time. For example, 9:00 AM in IRST is 11:30 PM in MDT (previous day).

What time is it in MDT right now?

MDT 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 IRST.