Chicago to London
+6hChicago
CDTSOURCELondon
BSTGreen rows indicate typical business hours (9 AM - 5 PM)
CDT and BST on the World Map
The map below highlights the CDT (Central Standard Time) and BST (Greenwich Mean Time) timezone regions across the globe.
CST – Central Standard Time
UTC-06:00Central Standard Time (CST) is the time zone for the central United States, Canada, and Mexico, 6 hours behind UTC.
- •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.
GMT – Greenwich Mean Time
UTC+00:00Greenwich Mean Time (GMT) is the mean solar time at the Royal Observatory in Greenwich, London. It is the same as UTC+00:00.
- •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.
About Chicago
WikipediaChicago operates on Central Time (CST/CDT), 1 hour behind New York. Home to CME and CBOE, Chicago is a global center for derivatives trading.
The Chicago Board of Trade is the world's oldest futures and options exchange.
About London
WikipediaLondon, where Greenwich Mean Time (GMT) originates, is the world's leading financial center alongside New York. The city bridges European and American business hours.
Big Ben is actually the name of the bell inside the Elizabeth Tower, not the tower itself.
Time Conversion Guide: Chicago to London
Chicago runs on Central Daylight Time (CDT) at UTC-05:00, currently observing daylight saving time. London runs on British Summer Time (BST) at UTC+01:00, also currently on daylight saving time. That puts Chicago 6 hours ahead of London — a difference of +6h at the current offsets.
In practice, when it is 9:00 AM in Chicago it is 3:00 PM in London. Midnight in Chicago is 6:00 AM in London. Because both zones shift for daylight saving, the gap between them only changes during the few weeks each year when their transition dates differ.
Chicago to London time conversion table
| Chicago (CDT) | London (BST) | Day |
|---|---|---|
| 12:00 AM | 6:00 AM | same day |
| 6:00 AM | 12:00 PM | same day |
| 7:00 AM | 1:00 PM | same day |
| 8:00 AM | 2:00 PM | same day |
| 9:00 AM | 3:00 PM | same day |
| 12:00 PM | 6:00 PM | same day |
| 3:00 PM | 9:00 PM | same day |
| 5:00 PM | 11:00 PM | same day |
| 6:00 PM | 12:00 AM | next day |
| 9:00 PM | 3:00 AM | next day |
Why people convert Chicago to London time
- Scheduling a call from Chicago to London: a 10:00 AM start in Chicago lands at 4:00 PM in London, so you can confirm the slot without doing the arithmetic yourself.
- Finding shared working hours: both Chicago and London are inside the 9-to-5 working day between 9:00 AM and 11:00 AM CDT time (3:00 PM–5:00 PM BST). That is roughly 2 hours of usable overlap.
- Coordinating a Chicago-based team with London contacts: quoting times in the other side's local clock — not your own — removes the single biggest source of missed meetings.
- Always state the zone abbreviation, not just the hour. "3:00 PM CDT" is unambiguous; "3 PM" across a +6h gap is not.
- Block 9:00 AM–11:00 AM CDT as the recurring meeting window if you work primarily from Chicago and need London colleagues present.
- Chicago: Clocks fall back on Sun, Nov 1, 2026. Re-check this page after that date because the offset changes and so does the +6h gap.
- London: Clocks fall back on Sun, Oct 25, 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 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.
Best time to call between Chicago and London
Both Chicago and London sit inside the 9 AM – 5 PM working day between 9:00 AM–11:00 AM CDT, which is 3:00 PM–5:00 PM BST. That gives roughly 2 hours of shared time — the safest window for a live call or meeting.
Business hours overlap
Chicago and London overlap for about 2 hours during the working day — enough for meetings if you avoid the edges of the window.
Chicago is 6 hours ahead of London (CDT UTC-05:00 → BST UTC+01:00). The shared working window is 9:00 AM–11:00 AM CDT. 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
London
☀ Currently in DST
Standard: UTC+00:00 · DST: UTC+01:00
Clocks fall back on Sun, Oct 25, 2026
Learn More About Time
Dive deeper into the fascinating world of timekeeping, time zones, and how they shape our global society:
Frequently Asked Questions
What is the time difference between Chicago and London?
Chicago (CDT, UTC-05:00) is 6 hours ahead of London (BST, UTC+01:00). The gap is currently +6h.
How do I convert Chicago time to London time?
Add +6h to Chicago local time. For example, 9:00 AM in Chicago is 3:00 PM in London.
What time is it in London right now?
London uses BST at UTC+01:00. Use the live converter at the top of this page — it updates in real time and already accounts for the +6h offset from Chicago.
What is the best time to call London from Chicago?
Call between 9:00 AM and 11:00 AM CDT — that maps to 3:00 PM–5:00 PM BST and keeps both parties inside the working day.
Which is ahead, Chicago or London?
Chicago is 6 hours ahead of London. When it is 12:00 PM in Chicago it is 6:00 PM in London.
Do Chicago and London use different time zones?
Chicago (USA) uses CDT at UTC-05:00, while London (UK) uses BST at UTC+01:00. The IANA identifiers are America/Chicago and Europe/London.
Does daylight saving time affect the Chicago–London difference?
Both zones observe DST, so the difference stays at +6h for most of the year and only changes during the weeks when their transition dates do not line up.
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 London?
Not normally. The +6h gap only pushes the date over for late-evening times.
What is the time difference between Chicago and London?
London is +6h 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 London in?
London, where Greenwich Mean Time (GMT) originates, is the world's leading financial center alongside New York. The city bridges European and American business hours.
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 London?
Standard business hours in London are 9:00 AM - 5:00 PM GMT.
What is the best time to schedule a call between Chicago and London?
The best overlap for a call is when both cities are in business hours. Chicago works 8:00 AM - 5:00 PM CST and London works 9:00 AM - 5:00 PM GMT (+6h difference). Try scheduling during the overlapping window for maximum convenience.
What currencies are used in Chicago and London?
Chicago uses USD ($) while London uses GBP (£). Check current exchange rates when planning travel or business between these cities.
How do Chicago and London compare in size?
Chicago has a population of approximately 2.7 million (metro: 9.5 million), while London has approximately 8.8 million (metro: 14.8 million).
What are the major landmarks in Chicago and London?
Chicago is known for Willis Tower, Millennium Park, Cloud Gate (The Bean). London is famous for Big Ben, Tower Bridge, Buckingham Palace.
Do Chicago and London have stock exchanges?
Yes. Chicago has the CME (Chicago Mercantile Exchange), CBOE and London has the LSE (London Stock Exchange). The +6h time difference affects trading hour overlaps between these exchanges.
Which countries use CST (Central Standard Time)?
CST is used in United States (Central), Canada (Manitoba, Saskatchewan), Mexico, Guatemala, Honduras, El Salvador, and 3 more countries.
Does CST observe daylight saving time?
Yes, CST switches to CDT during summer months.
What are some interesting facts about CST?
CST covers 20 US states fully or partially. Chicago and Houston are the two largest cities in the Central Time Zone.
Which cities are in the GMT timezone?
Major cities in the GMT timezone include London, Dublin, Lisbon, Accra, Reykjavik, Edinburgh, Casablanca, Dakar.
What is the UTC offset for GMT?
Greenwich Mean Time (GMT) is at UTC+00:00. During daylight saving time, it shifts to BST.
What should I know about the GMT timezone?
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.
When is it midnight in Chicago, what time is it in London?
When it is 12:00 AM (midnight) in Chicago (CST), it is +6h later in London (GMT).
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