London to Chicago
-6hLondon
BSTSOURCEChicago
CDTGreen rows indicate typical business hours (9 AM - 5 PM)
BST and CDT on the World Map
The map below highlights the BST (Greenwich Mean Time) and CDT (Central Standard Time) timezone regions across the globe.
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.
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.
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.
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.
Time Conversion Guide: London to Chicago
London runs on British Summer Time (BST) at UTC+01:00, currently observing daylight saving time. Chicago runs on Central Daylight Time (CDT) at UTC-05:00, also currently on daylight saving time. That puts London 6 hours behind Chicago — a difference of -6h at the current offsets.
In practice, when it is 9:00 AM in London it is 3:00 AM in Chicago. Midnight in London is 6:00 PM in Chicago. Because both zones shift for daylight saving, the gap between them only changes during the few weeks each year when their transition dates differ.
London to Chicago time conversion table
| London (BST) | Chicago (CDT) | Day |
|---|---|---|
| 12:00 AM | 6:00 PM | previous day |
| 6:00 AM | 12:00 AM | same day |
| 7:00 AM | 1:00 AM | same day |
| 8:00 AM | 2:00 AM | same day |
| 9:00 AM | 3:00 AM | same day |
| 12:00 PM | 6:00 AM | same day |
| 3:00 PM | 9:00 AM | same day |
| 5:00 PM | 11:00 AM | same day |
| 6:00 PM | 12:00 PM | same day |
| 9:00 PM | 3:00 PM | same day |
Why people convert London to Chicago time
- Scheduling a call from London to Chicago: a 10:00 AM start in London lands at 4:00 AM in Chicago, so you can confirm the slot without doing the arithmetic yourself.
- Finding shared working hours: both London and Chicago are inside the 9-to-5 working day between 3:00 PM and 5:00 PM BST time (9:00 AM–11:00 AM CDT). That is roughly 2 hours of usable overlap.
- Keeping family and friends in sync: knowing that 8:00 PM in London is 2:00 PM in Chicago makes it easy to avoid calling at 3 AM.
- Always state the zone abbreviation, not just the hour. "3:00 PM BST" is unambiguous; "3 PM" across a -6h gap is not.
- Block 3:00 PM–5:00 PM BST as the recurring meeting window if you work primarily from London and need Chicago colleagues present.
- London: Clocks fall back on Sun, Oct 25, 2026. Re-check this page after that date because the offset changes and so does the -6h gap.
- 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 London and Chicago
Both London and Chicago sit inside the 9 AM – 5 PM working day between 3:00 PM–5:00 PM BST, which is 9:00 AM–11:00 AM CDT. That gives roughly 2 hours of shared time — the safest window for a live call or meeting.
Business hours overlap
London and Chicago overlap for about 2 hours during the working day — enough for meetings if you avoid the edges of the window.
London is 6 hours behind Chicago (BST UTC+01:00 → CDT UTC-05:00). The shared working window is 3:00 PM–5:00 PM BST. Remember to re-check around daylight-saving transitions.
🕐 Daylight Saving Time Info
London
☀ 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:
Frequently Asked Questions
What is the time difference between London and Chicago?
London (BST, UTC+01:00) is 6 hours behind Chicago (CDT, UTC-05:00). The gap is currently -6h.
How do I convert London time to Chicago time?
Add -6h to London local time. For example, 9:00 AM in London is 3:00 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 -6h offset from London.
What is the best time to call Chicago from London?
Call between 3:00 PM and 5:00 PM BST — that maps to 9:00 AM–11:00 AM CDT and keeps both parties inside the working day.
Which is behind, London or Chicago?
London is 6 hours behind Chicago. When it is 12:00 PM in London it is 6:00 AM in Chicago.
Do London and Chicago use different time zones?
London (UK) uses BST at UTC+01:00, while Chicago (USA) uses CDT at UTC-05:00. The IANA identifiers are Europe/London and America/Chicago.
Does daylight saving time affect the London–Chicago 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 London's time zone?
BST also covers London, Dublin, Lisbon, Accra, Reykjavik, Edinburgh, Casablanca, Dakar and 5 more.
Which countries use BST, London's zone?
BST is used in United Kingdom, Ireland, Iceland, Portugal (mainland), Ghana, Senegal, Mali, Mauritania and 7 more.
Is there a day difference between London and Chicago?
Not normally. The -6h gap only pushes the date over the previous day.
What is the time difference between London and Chicago?
Chicago is -6h from London.
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 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 London?
Standard business hours in London are 9:00 AM - 5:00 PM GMT.
What are the business hours in Chicago?
Standard business hours in Chicago are 8:00 AM - 5:00 PM CST.
What is the best time to schedule a call between London and Chicago?
The best overlap for a call is when both cities are in business hours. London works 9:00 AM - 5:00 PM GMT and Chicago works 8:00 AM - 5:00 PM CST (-6h difference). Try scheduling during the overlapping window for maximum convenience.
What currencies are used in London and Chicago?
London uses GBP (£) while Chicago uses USD ($). Check current exchange rates when planning travel or business between these cities.
How do London and Chicago compare in size?
London has a population of approximately 8.8 million (metro: 14.8 million), while Chicago has approximately 2.7 million (metro: 9.5 million).
What are the major landmarks in London and Chicago?
London is known for Big Ben, Tower Bridge, Buckingham Palace. Chicago is famous for Willis Tower, Millennium Park, Cloud Gate (The Bean).
Do London and Chicago have stock exchanges?
Yes. London has the LSE (London Stock Exchange) and Chicago has the CME (Chicago Mercantile Exchange), CBOE. The -6h time difference affects trading hour overlaps between these exchanges.
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.
Which cities are in the CST timezone?
Major cities in the CST timezone include Chicago, Houston, Dallas, San Antonio, Mexico City, Austin, Winnipeg, Memphis.
What is the UTC offset for CST?
Central Standard Time (CST) is at UTC-06:00. During daylight saving time, it shifts to CDT.
What should I know about the CST timezone?
CST covers 20 US states fully or partially. Chicago and Houston are the two largest cities in the Central Time Zone.
When is it midnight in London, what time is it in Chicago?
When it is 12:00 AM (midnight) in London (GMT), it is -6h later in Chicago (CST).
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