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).

Chicago to Sydney

+15h

Chicago

CDTSOURCE

USA · UTC-05:00☀ DST active

HH12

MM00

12:00 (24-hr)

12 AM6 AM12 PM6 PM12 AM

Sydney

AEST

Australia · UTC+10:00DST observed

HH03

MM00

(next day)03:00 (24-hr)

12 AM6 AM12 PM6 PM12 AM

Quick Reference

Time Conversion Table

Chicago

Sydney

12:00 AM

3:00 PM

2:00 AM

5:00 PM

4:00 AM

7:00 PM

6:00 AM

9:00 PM

8:00 AM

11:00 PM

10:00 AM

1:00 AM+1

12:00 PM

3:00 AM+1

2:00 PM

5:00 AM+1

4:00 PM

7:00 AM+1

6:00 PM

9:00 AM+1

8:00 PM

11:00 AM+1

10:00 PM

1:00 PM+1

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

CDT and AEST on the World Map

The map below highlights the CDT (Central Standard Time) and AEST (Australian Eastern Standard Time) timezone regions across the globe.

CDT Zone

→

AEST 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

AEST – Australian Eastern Standard Time

UTC+10:00

Australian Eastern Standard Time (AEST) covers eastern Australia, 10 hours ahead of UTC.

Countries in AEST

Australia (NSW, VIC, QLD, TAS, ACT)Papua New Guinea

Major Cities in AEST

SydneyMelbourneBrisbaneCanberraHobartGold Coast

Key Facts about AEST

•Queensland does not observe daylight saving time, staying on AEST year-round.
•Sydney and Melbourne switch to AEDT (UTC+11:00) in summer.
•The Australian Securities Exchange (ASX) operates on AEST/AEDT.
•AEST is 15 hours ahead of EST during winter.

Daylight Saving:Yes – switches to AEDT

Learn more about AEST 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 Sydney

Wikipedia

Sydney operates on Australian Eastern Standard Time (AEST/AEDT). As Australia's financial capital, Sydney opens global markets at the start of the business day.

Population:5.4 million

Metro:5.4 million

Business Hours:9:00 AM - 5:00 PM AEST

Currency:AUD (A$)

Stock Exchange:ASX (Australian Securities Exchange)

Key Landmarks

Sydney Opera HouseSydney Harbour BridgeBondi BeachDarling HarbourRoyal Botanic Garden

Did You Know?

Sydney is one of the first major cities to welcome the New Year.

Learn more about AEST timezone →

Chicago vs Sydney: Offsets, DST and Best Call Times

Chicago runs on Central Daylight Time (CDT) at UTC-05:00, currently observing daylight saving time. Sydney runs on Australian Eastern Standard Time (AEST) at UTC+10:00. That puts Chicago 15 hours ahead of Sydney — a difference of +15h at the current offsets.

In practice, when it is 9:00 AM in Chicago it is 12:00 AM in Sydney on the next day. Midnight in Chicago is 3:00 PM in Sydney.Chicago observes daylight saving time while Sydney does not, so the gap narrows or widens by an hour part of the year.

Chicago to Sydney time conversion table

Chicago (CDT)	Sydney (AEST)	Day
12:00 AM	3:00 PM	same day
6:00 AM	9:00 PM	same day
7:00 AM	10:00 PM	same day
8:00 AM	11:00 PM	same day
9:00 AM	12:00 AM	next day
12:00 PM	3:00 AM	next day
3:00 PM	6:00 AM	next day
5:00 PM	8:00 AM	next day
6:00 PM	9:00 AM	next day
9:00 PM	12:00 PM	next day

Why people convert Chicago to Sydney time

Scheduling a call from Chicago to Sydney: a 10:00 AM start in Chicago lands at 1:00 AM in Sydney the next day, so you can confirm the slot without doing the arithmetic yourself.
Handling a +15h gap: Chicago and Sydney 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 Sydney is 12:00 AM in Chicago.
Watching a live event or market open: Chicago viewers need 12:00 AM in Sydney to catch a 9:00 AM start there, and 9:00 AM if the event is anchored to Chicago.

Always state the zone abbreviation, not just the hour. "3:00 PM CDT" is unambiguous; "3 PM" across a +15h gap is not.
With a +15h gap there is no shared 9-to-5 window, so alternate the early start: one week Chicago takes the early slot, the next week Sydney 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 +15h gap.
Sydney: Clocks spring forward on Sat, Oct 3, 2026. Any meeting series spanning that date will shift by an hour in local time.

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 AEST (Australian Eastern Standard Time)

Australian Eastern Standard Time (AEST) is used in the eastern states of Australia including New South Wales, Victoria, Queensland, Tasmania, and the ACT. During summer (October to April), NSW, VIC, TAS, and ACT switch to Australian Eastern Daylight Time (AEDT, UTC+11:00), while Queensland remains on AEST year-round.

Best time to call between Chicago and Sydney

With a +15h offset there is no overlap inside a normal 9 AM – 5 PM day. Sydney opens at 9:00 AM AEST, which is 12:00 AM in Chicago, so real-time calls need an early-morning or late-evening slot on one side.

Business hours overlap

Chicago and Sydney have no shared working hours because of the +15h gap. Teams need to alternate early starts or rely on asynchronous handovers.

Chicago is 15 hours ahead of Sydney (CDT UTC-05:00 → AEST UTC+10:00). 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

Chicago

☀ Currently in DST

Standard: UTC-06:00 · DST: UTC-05:00

Clocks fall back on Sun, Nov 1, 2026

Sydney

❄ Currently in Standard Time

Standard: UTC+10:00 · DST: UTC+11:00

Clocks spring forward on Sat, Oct 3, 2026

⚠ These locations are currently in different DST states, so the time difference may change when clocks adjust.

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 Sydney?

Chicago (CDT, UTC-05:00) is 15 hours ahead of Sydney (AEST, UTC+10:00). The gap is currently +15h.

How do I convert Chicago time to Sydney time?

Add +15h to Chicago local time. For example, 9:00 AM in Chicago is 12:00 AM in Sydney (next day).

What time is it in Sydney right now?

Sydney uses AEST at UTC+10:00. Use the live converter at the top of this page — it updates in real time and already accounts for the +15h offset from Chicago.

What is the best time to call Sydney from Chicago?

There is no shared working-hours window because of the +15h gap. The closest option is 1:00 PM in Chicago, which is 4:00 AM in Sydney.

Which is ahead, Chicago or Sydney?

Chicago is 15 hours ahead of Sydney. When it is 12:00 PM in Chicago it is 3:00 AM in Sydney.

Do Chicago and Sydney use different time zones?

Chicago (USA) uses CDT at UTC-05:00, while Sydney (Australia) uses AEST at UTC+10:00. The IANA identifiers are America/Chicago and Australia/Sydney.

Does daylight saving time affect the Chicago–Sydney difference?

Yes at the moment: Chicago is on daylight saving time and Sydney is not, so the +15h 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 Sydney?

Sometimes. The +15h gap is large enough that 8:00 PM or later in Chicago already falls on the next day in Sydney.

What is the time difference between Chicago and Sydney?

Sydney is +15h 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 Sydney in?

Sydney operates on Australian Eastern Standard Time (AEST/AEDT). As Australia's financial capital, Sydney opens global markets at the start of the business day.

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 Sydney?

Standard business hours in Sydney are 9:00 AM - 5:00 PM AEST.

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

The best overlap for a call is when both cities are in business hours. Chicago works 8:00 AM - 5:00 PM CST and Sydney works 9:00 AM - 5:00 PM AEST (+15h difference). Try scheduling during the overlapping window for maximum convenience.

What currencies are used in Chicago and Sydney?

Chicago uses USD ($) while Sydney uses AUD (A$). Check current exchange rates when planning travel or business between these cities.

How do Chicago and Sydney compare in size?

Chicago has a population of approximately 2.7 million (metro: 9.5 million), while Sydney has approximately 5.4 million (metro: 5.4 million).

What are the major landmarks in Chicago and Sydney?

Chicago is known for Willis Tower, Millennium Park, Cloud Gate (The Bean). Sydney is famous for Sydney Opera House, Sydney Harbour Bridge, Bondi Beach.

Do Chicago and Sydney have stock exchanges?

Yes. Chicago has the CME (Chicago Mercantile Exchange), CBOE and Sydney has the ASX (Australian Securities Exchange). The +15h time difference affects trading hour overlaps between these exchanges.