Chicago to London Time Converter
Convert time between Chicago and London. Right now, Chicago is 6 hours behind London.
Time Zone Converter
Click any hour to see what it lands on in every city. The first row's hours run 12am to 11pm — every other row is its local time at the same instant.
When it's this time in Chicago:
| Chicago | London |
|---|---|
| 6:00 AM | 12:00 PM |
| 9:00 AM | 3:00 PM |
| 12:00 PM | 6:00 PM |
| 3:00 PM | 9:00 PM |
| 6:00 PM | 12:00 AM |
| 9:00 PM | 3:00 AM |
About CST and GMT
CST (Central Time (US)) covers USA and Mexico and is anchored to the IANA zone America/Chicago. It observes daylight saving time, so the offset shifts by one hour twice a year.
GMT (Greenwich Mean Time) covers UK, Ireland, Iceland, and Portugal via Europe/London. It observes daylight saving time, so the gap between these two zones shifts twice a year.
Because at least one of these zones uses DST, the time difference between CST and GMT is not constant — it shifts by an hour during the spring and autumn DST transitions. The hour grid below recomputes the difference for any specific date you click, using the IANA rules baked into your browser.
FAQ
- How many hours difference between CST and GMT?
- Right now, CST is 6 hours behind GMT. Because at least one of these zones observes daylight saving time, the gap shifts by an hour twice a year (spring and autumn). The hour grid above recomputes correctly for any specific date.
- What time is 9 AM CST in GMT?
- 9 AM CST (Chicago) is 3:00 PM GMT (London) today. Click any cell in the grid above to convert other times — the math handles DST and half-hour offsets correctly.
- Does CST observe daylight saving time?
- Yes. Central Time (US) shifts forward by one hour in the spring and back in the autumn. The exact dates depend on the country's rules — the IANA timezone database tracks them all and updates automatically.
- What's the IANA timezone identifier for CST and GMT?
- CST → America/Chicago. GMT → Europe/London. We use IANA identifiers (not GMT offsets) as the source of truth so historical and future dates remain accurate, including across DST changes and political timezone shifts.
- Where can I see the overlap between CST and GMT working hours?
- Click "Working hrs" in the toolbar above to highlight hours where all selected cities have overlapping business hours. The amber highlight shows which columns work for scheduling meetings across time zones.
- Which countries use CST and GMT?
- CST (Central Time (US)) is used in USA and Mexico. GMT (Greenwich Mean Time) is used in UK, Ireland, Iceland, and Portugal. If you're converting time between any of these countries, this is the right page.