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 Mexico City

-9h 30m

IRST

IRSTSOURCE

UTC+03:30

HH12

MM00

12:00 (24-hr)

12 AM6 AM12 PM6 PM12 AM

Mexico City

CST

Mexico · UTC-06:00

HH02

MM30

02:30 (24-hr)

12 AM6 AM12 PM6 PM12 AM

Quick Reference

Time Conversion Table

IRST

Mexico City

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 CST on the World Map

The map below highlights the IRST (Iran Standard Time) and CST (Central Standard Time) timezone regions across the globe.

IRST Zone

→

CST 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

CST – Central Standard Time

UTC-06:00

Central Standard Time (CST) is the time zone for the central United States, Canada, and Mexico, 6 hours behind UTC.

Countries in CST

United States (Central)Canada (Manitoba, Saskatchewan)MexicoGuatemalaHondurasEl SalvadorCosta RicaNicaraguaBelize

Major Cities in CST

ChicagoHoustonDallasSan AntonioMexico CityAustinWinnipegMemphisMilwaukeeNashvilleKansas CityNew OrleansMinneapolisGuatemala City

Key Facts about CST

•CST covers 20 US states fully or partially.
•Chicago and Houston are the two largest cities in the Central Time Zone.
•Mexico City, one of the world's most populous cities, operates on CST.
•CST is 1 hour behind EST and 2 hours ahead of PST.

Daylight Saving:Yes – switches to CDT

Learn more about CST on Wikipedia

About Mexico City

Wikipedia

Mexico City operates on Central Time (CST/CDT), same as Chicago. As North America's largest city, Mexico City bridges US and Latin American business hours.

Population:9.2 million

Metro:21.8 million

Business Hours:9:00 AM - 6:00 PM CST

Currency:MXN ($)

Stock Exchange:BMV (Bolsa Mexicana de Valores)

Key Landmarks

ZócaloPalacio de Bellas ArtesChapultepec CastleTemplo MayorAngel of Independence

Did You Know?

Mexico City is the oldest capital city in the Americas.

Learn more about CST timezone →

IRST to Mexico City Time Difference – Complete Guide

IRST runs on Iran Standard Time (IRST) at UTC+03:30. Mexico City runs on Central Standard Time (CST) at UTC-06:00. That puts IRST 9 hours 30 minutes behind Mexico City — 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 Mexico City on the previous day. Midnight in IRST is 2:30 PM in Mexico City. Neither zone observes daylight saving time, so the offset between them stays constant all year.

IRST to Mexico City time conversion table

IRST (IRST)	Mexico City (CST)	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 Mexico City time

Scheduling a call from IRST to Mexico City: a 10:00 AM start in IRST lands at 12:30 AM in Mexico City, so you can confirm the slot without doing the arithmetic yourself.
Handling a -9h 30m gap: IRST and Mexico City 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 Mexico City is 11:30 PM in IRST.
Keeping family and friends in sync: knowing that 8:00 PM in IRST is 10:30 AM in Mexico City makes it easy to avoid calling at 3 AM.

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 Mexico City 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 CST (Central Standard Time)

Central Standard Time (CST) covers the central region of North America. It is the second most populous time zone in the US, including major cities like Chicago, Houston, and Dallas. CST is also used in Mexico City and much of Central America including Guatemala, Honduras, El Salvador, and Costa Rica. During summer, most of the US and Canada switch to Central Daylight Time (CDT, UTC-05:00), while Mexico and Central American countries generally remain on CST.

Best time to call between IRST and Mexico City

With a -9h 30m offset there is no overlap inside a normal 9 AM – 5 PM day. Mexico City opens at 9:00 AM CST, 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 Mexico City 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 Mexico City (IRST UTC+03:30 → CST 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.

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 Mexico City?

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

How do I convert IRST time to Mexico City time?

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

What time is it in Mexico City right now?

Mexico City uses CST 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.

What is the best time to call Mexico City from IRST?

There is no shared working-hours window because of the -9h 30m gap. The closest option is 1:00 PM in IRST, which is 3:30 AM in Mexico City.

Which is behind, IRST or Mexico City?

IRST is 9 hours 30 minutes behind Mexico City. When it is 12:00 PM in IRST it is 2:30 AM in Mexico City.

Do IRST and Mexico City use different time zones?

IRST uses IRST at UTC+03:30, while Mexico City (Mexico) uses CST at UTC-06:00. The IANA identifiers are Asia/Tehran and America/Mexico_City.

Does daylight saving time affect the IRST–Mexico City difference?

Neither zone observes daylight saving time, so the -9h 30m offset between IRST and Mexico City is fixed all year.

Which other cities share IRST's time zone?

IRST also covers Tehran, Isfahan, Mashhad, Tabriz, Shiraz, Karaj.

Which countries use IRST, IRST's zone?

IRST is used in Iran.

Is there a day difference between IRST and Mexico City?

Not normally. The -9h 30m gap only pushes the date over the previous day.

What is the time difference between IRST and Mexico City?

Mexico City is -9h 30m from IRST.

What timezone is IRST in?

IRST operates on its local timezone.

What timezone is Mexico City in?

Mexico City operates on Central Time (CST/CDT), same as Chicago. As North America's largest city, Mexico City bridges US and Latin American business hours.