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).

GMT to Chicago

-5h

GMT

GMTSOURCE

UTC+01:00☀ DST active

HH12

MM00

12:00 (24-hr)

12 AM6 AM12 PM6 PM12 AM

Chicago

CDT

USA · UTC-05:00☀ DST active

HH07

MM00

07:00 (24-hr)

12 AM6 AM12 PM6 PM12 AM

Quick Reference

Time Conversion Table

GMT

Chicago

12:00 AM

6:00 PM-1

2:00 AM

8:00 PM-1

4:00 AM

10:00 PM-1

6:00 AM

12:00 AM

8:00 AM

2:00 AM

10:00 AM

4:00 AM

12:00 PM

6:00 AM

2:00 PM

8:00 AM

4:00 PM

10:00 AM

6:00 PM

12:00 PM

8:00 PM

2:00 PM

10:00 PM

4:00 PM

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

GMT and CDT on the World Map

The map below highlights the GMT (Greenwich Mean Time) and CDT (Central Standard Time) timezone regions across the globe.

GMT Zone

→

CDT Zone

Explore all world timezones interactively →

GMT – Greenwich Mean Time

UTC+00:00

Greenwich Mean Time (GMT) is the mean solar time at the Royal Observatory in Greenwich, London. It is the same as UTC+00:00.

Countries in GMT

United KingdomIrelandIcelandPortugal (mainland)GhanaSenegalMaliMauritaniaGambiaGuineaSierra LeoneLiberiaIvory CoastBurkina FasoMorocco (historically)

Major Cities in GMT

LondonDublinLisbonAccraReykjavikEdinburghCasablancaDakarBamakoAbidjanConakryFreetownMonrovia

Key Facts about GMT

•GMT is based on the Prime Meridian (0° longitude) passing through Greenwich, London.
•The Royal Observatory in Greenwich has been the reference point for GMT since 1884.
•GMT and UTC are often used interchangeably, but UTC is based on atomic clocks.
•Iceland uses GMT year-round and never observes daylight saving time.
•The UK switches from GMT to BST (British Summer Time) in late March each year.

Daylight Saving:Yes – switches to BST

Learn more about GMT 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 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 →

GMT vs Chicago: Offsets, DST and Best Call Times

GMT runs on Greenwich Mean Time (GMT) at UTC+00:00. Chicago runs on Central Daylight Time (CDT) at UTC-05:00, also currently on daylight saving time. That puts GMT 5 hours behind Chicago — a difference of -5h at the current offsets.

In practice, when it is 9:00 AM in GMT it is 4:00 AM in Chicago. Midnight in GMT is 7:00 PM in Chicago.Chicago observes daylight saving time while GMT does not, so the gap narrows or widens by an hour part of the year.

GMT to Chicago time conversion table

GMT (GMT)	Chicago (CDT)	Day
12:00 AM	7:00 PM	previous day
6:00 AM	1:00 AM	same day
7:00 AM	2:00 AM	same day
8:00 AM	3:00 AM	same day
9:00 AM	4:00 AM	same day
12:00 PM	7:00 AM	same day
3:00 PM	10:00 AM	same day
5:00 PM	12:00 PM	same day
6:00 PM	1:00 PM	same day
9:00 PM	4:00 PM	same day

Why people convert GMT to Chicago time

Scheduling a call from GMT to Chicago: a 10:00 AM start in GMT lands at 5:00 AM in Chicago, so you can confirm the slot without doing the arithmetic yourself.
Finding shared working hours: both GMT and Chicago are inside the 9-to-5 working day between 2:00 PM and 5:00 PM GMT time (9:00 AM–12:00 PM CDT). That is roughly 3 hours of usable overlap.
Booking travel or deliveries: tracking Chicago local time against GMT keeps pickup windows and arrival estimates honest across the -5h offset.

Always state the zone abbreviation, not just the hour. "3:00 PM GMT" is unambiguous; "3 PM" across a -5h gap is not.
Block 2:00 PM–5:00 PM GMT as the recurring meeting window if you work primarily from GMT and need Chicago colleagues present.
Chicago: Clocks fall back on Sun, Nov 1, 2026. Any meeting series spanning that date will shift by an hour in local time.

About GMT (Greenwich Mean Time)

Greenwich Mean Time (GMT) is the clock time at the Royal Observatory in Greenwich, London, which sits on the Prime Meridian (0° longitude). GMT serves as the reference point from which all other time zones are calculated. The United Kingdom uses GMT during winter months and switches to British Summer Time (BST, UTC+01:00) from late March to late October. Several West African nations use GMT year-round. GMT is often used interchangeably with UTC (Coordinated Universal Time), although technically they are different – UTC is based on atomic clocks while GMT is based on Earth's rotation.

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 GMT and Chicago

Both GMT and Chicago sit inside the 9 AM – 5 PM working day between 2:00 PM–5:00 PM GMT, which is 9:00 AM–12:00 PM CDT. That gives roughly 3 hours of shared time — the safest window for a live call or meeting.

Business hours overlap

GMT and Chicago overlap for about 3 hours during the working day — enough for meetings if you avoid the edges of the window.

GMT is 5 hours behind Chicago (GMT UTC+00:00 → CDT UTC-05:00). The shared working window is 2:00 PM–5:00 PM GMT. Remember to re-check around daylight-saving transitions.

🕐 Daylight Saving Time Info

GMT

☀ Currently in DST

Standard: UTC+00:00 · DST: UTC+01:00

Clocks fall back on Sun, Oct 25, 2026

Chicago

☀ Currently in DST

Standard: UTC-06:00 · DST: UTC-05:00

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 GMT and Chicago?

GMT (GMT, UTC+00:00) is 5 hours behind Chicago (CDT, UTC-05:00). The gap is currently -5h.

How do I convert GMT time to Chicago time?

Add -5h to GMT local time. For example, 9:00 AM in GMT is 4:00 AM in Chicago.

What time is it in Chicago right now?

Chicago uses CDT at UTC-05:00. Use the live converter at the top of this page — it updates in real time and already accounts for the -5h offset from GMT.

What is the best time to call Chicago from GMT?

Call between 2:00 PM and 5:00 PM GMT — that maps to 9:00 AM–12:00 PM CDT and keeps both parties inside the working day.

Which is behind, GMT or Chicago?

GMT is 5 hours behind Chicago. When it is 12:00 PM in GMT it is 7:00 AM in Chicago.

Do GMT and Chicago use different time zones?

GMT uses GMT at UTC+00:00, while Chicago (USA) uses CDT at UTC-05:00. The IANA identifiers are Europe/London and America/Chicago.

Does daylight saving time affect the GMT–Chicago difference?

Yes at the moment: Chicago is on daylight saving time and GMT is not, so the -5h gap shifts by an hour when exactly one of them changes clocks.

Which other cities share GMT's time zone?

GMT also covers London, Dublin, Lisbon, Accra, Reykjavik, Edinburgh, Casablanca, Dakar and 5 more.

Which countries use GMT, GMT's zone?

GMT is used in United Kingdom, Ireland, Iceland, Portugal (mainland), Ghana, Senegal, Mali, Mauritania and 7 more.

Is there a day difference between GMT and Chicago?

Not normally. The -5h gap only pushes the date over the previous day.

What is the time difference between GMT and Chicago?

Chicago is -5h from GMT.

What timezone is GMT in?

GMT operates on its local timezone.

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 are the business hours in Chicago?

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

Which countries use GMT (Greenwich Mean Time)?

GMT is used in United Kingdom, Ireland, Iceland, Portugal (mainland), Ghana, Senegal, and 9 more countries.

Does GMT observe daylight saving time?

Yes, GMT switches to BST during summer months.

What are some interesting facts about GMT?

GMT is based on the Prime Meridian (0° longitude) passing through Greenwich, London. The Royal Observatory in Greenwich has been the reference point for GMT since 1884.