Does it handle Daylight Saving Time?

Yes, the tool automatically adjusts for Daylight Saving Time based on the specific date you select, ensuring accurate conversions year-round.

Can I add multiple cities?

Yes, you can add as many cities as you need to the dashboard to compare times across your entire global network simultaneously.

Chicago to Tehran

+8h 30m

Chicago

CDTSOURCE

USA · UTC-05:00☀ DST active

HH12

MM00

12:00 (24-hr)

12 AM6 AM12 PM6 PM12 AM

Tehran

IRST

Iran · UTC+03:30

HH08

MM30

20:30 (24-hr)

12 AM6 AM12 PM6 PM12 AM

Quick Reference

Time Conversion Table

Chicago

Tehran

12:00 AM

8:30 AM

2:00 AM

10:30 AM

4:00 AM

12:30 PM

6:00 AM

2:30 PM

8:00 AM

4:30 PM

10:00 AM

6:30 PM

12:00 PM

8:30 PM

2:00 PM

10:30 PM

4:00 PM

12:30 AM+1

6:00 PM

2:30 AM+1

8:00 PM

4:30 AM+1

10:00 PM

6:30 AM+1

Green rows indicate typical business hours (9 AM - 5 PM)

CDT and IRST on the World Map

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

CDT Zone

→

IRST Zone

Explore all world timezones interactively →

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

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

About Chicago

Wikipedia

Chicago operates on Central Time (CST/CDT), 1 hour behind New York. Home to CME and CBOE, Chicago is a global center for derivatives trading.

Population:2.7 million

Metro:9.5 million

Business Hours:8:00 AM - 5:00 PM CST

Currency:USD ($)

Stock Exchange:CME (Chicago Mercantile Exchange), CBOE

Key Landmarks

Willis TowerMillennium ParkCloud Gate (The Bean)Navy PierArt Institute of Chicago

Did You Know?

The Chicago Board of Trade is the world's oldest futures and options exchange.

Learn more about CDT timezone →

About Tehran

Wikipedia

Tehran operates on Iran Standard Time (IRST), UTC+3:30. Iran's unique half-hour offset makes Tehran time distinctive for regional business coordination.

Population:9.4 million

Metro:16.8 million

Business Hours:8:00 AM - 4:00 PM IRST

Currency:IRR (﷼)

Stock Exchange:TSE (Tehran Stock Exchange)

Key Landmarks

Azadi TowerGolestan PalaceGrand BazaarMilad TowerTabiat Bridge

Did You Know?

Iran Standard Time (IRST) is one of few timezones with a 30-minute offset (UTC+3:30).

Learn more about IRST timezone →

Time Conversion Guide: Chicago to Tehran

Chicago runs on Central Daylight Time (CDT) at UTC-05:00, currently observing daylight saving time. Tehran runs on Iran Standard Time (IRST) at UTC+03:30. That puts Chicago 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 Chicago it is 5:30 PM in Tehran. Midnight in Chicago is 8:30 AM in Tehran.Chicago observes daylight saving time while Tehran does not, so the gap narrows or widens by an hour part of the year.

Chicago to Tehran time conversion table

Chicago (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 Chicago to Tehran time

Scheduling a call from Chicago to Tehran: a 10:00 AM start in Chicago lands at 6:30 PM in Tehran, so you can confirm the slot without doing the arithmetic yourself.
Handling a +8h 30m gap: Chicago 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 Chicago.
Booking travel or deliveries: tracking Tehran local time against Chicago keeps pickup windows and arrival estimates honest across the +8h 30m offset.

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 Chicago takes the early slot, the next week Tehran does.
Chicago: Clocks fall back on Sun, Nov 1, 2026. Re-check this page after that date because the offset changes and so does the +8h 30m gap.

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.

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 Chicago 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 Chicago, so real-time calls need an early-morning or late-evening slot on one side.

Business hours overlap

Chicago and Tehran have no shared working hours because of the +8h 30m gap. Teams need to alternate early starts or rely on asynchronous handovers.

Chicago 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

Chicago

☀ 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:

⏳

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 Chicago and Tehran?

Chicago (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 Chicago time to Tehran time?

Add +8h 30m to Chicago local time. For example, 9:00 AM in Chicago 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 Chicago.

What is the best time to call Tehran from Chicago?

There is no shared working-hours window because of the +8h 30m gap. The closest option is 1:00 PM in Chicago, which is 9:30 PM in Tehran.

Which is ahead, Chicago or Tehran?

Chicago is 8 hours 30 minutes ahead of Tehran. When it is 12:00 PM in Chicago it is 8:30 PM in Tehran.

Do Chicago and Tehran use different time zones?

Chicago (USA) 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 Chicago–Tehran difference?

Yes at the moment: Chicago is on daylight saving time and Tehran is not, so the +8h 30m gap shifts by an hour when exactly one of them changes clocks.

Which other cities share Chicago's time zone?

CDT also covers Chicago, Houston, Dallas, San Antonio, Mexico City, Austin, Winnipeg, Memphis and 6 more.

Which countries use CDT, Chicago's zone?

CDT is used in United States (Central), Canada (Manitoba, Saskatchewan), Mexico, Guatemala, Honduras, El Salvador, Costa Rica, Nicaragua and 1 more.

Is there a day difference between Chicago and Tehran?

Not normally. The +8h 30m gap only pushes the date over for late-evening times.

What is the time difference between Chicago and Tehran?

Tehran is +8h 30m from Chicago.

What timezone is Chicago in?

Chicago operates on Central Time (CST/CDT), 1 hour behind New York. Home to CME and CBOE, Chicago is a global center for derivatives trading.

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 Chicago?

Standard business hours in Chicago are 8:00 AM - 5:00 PM CST.

What are the business hours in Tehran?

Standard business hours in Tehran are 8:00 AM - 4:00 PM IRST.

What is the best time to schedule a call between Chicago and Tehran?

The best overlap for a call is when both cities are in business hours. Chicago works 8:00 AM - 5:00 PM CST and Tehran works 8:00 AM - 4:00 PM IRST (+8h 30m difference). Try scheduling during the overlapping window for maximum convenience.

What currencies are used in Chicago and Tehran?

Chicago uses USD ($) while Tehran uses IRR (﷼). Check current exchange rates when planning travel or business between these cities.

How do Chicago and Tehran compare in size?

Chicago has a population of approximately 2.7 million (metro: 9.5 million), while Tehran has approximately 9.4 million (metro: 16.8 million).

What are the major landmarks in Chicago and Tehran?

Chicago is known for Willis Tower, Millennium Park, Cloud Gate (The Bean). Tehran is famous for Azadi Tower, Golestan Palace, Grand Bazaar.

Do Chicago and Tehran have stock exchanges?

Yes. Chicago has the CME (Chicago Mercantile Exchange), CBOE and Tehran has the TSE (Tehran Stock Exchange). The +8h 30m time difference affects trading hour overlaps between these exchanges.