GMT to CST Time Zone Converter
This converts London time (GMT in winter, BST in summer) to US Central Time — Chicago, Dallas, Mexico City. Central runs 6 hours behind London for most of the year. Both sides observe daylight saving but change clocks on different dates, so the gap is briefly off by an hour each spring and fall. The tool applies the right offset for your date.
Enter a date and time to convert.
Daylight saving is applied automatically for the date you pick. Labels like PST/EST name the zone (Pacific/Eastern); the real abbreviation shifts to PDT/EDT during daylight saving, and gmt here means London (GMT in winter, BST in summer) while utc stays fixed.
The time difference
US Central Time usually sits 6 hours behind London — subtract 6 from the London clock. Both regions observe daylight saving, so for most of the year they shift together and the 6-hour gap holds. But they don't switch on the same day: the US moves a few weeks apart from the UK, so during two short windows the difference narrows to 5 hours before returning to 6.
A worked example
Take 9:00 AM in London. On January 15, 2026 (winter), that is 3:00 AM CST in Chicago. On July 15, 2026 (summer), it's still 3:00 AM CDT — the usual 6-hour gap holds at both anchor dates. That's the small hours of the morning in the Central zone, and still the same calendar day.
Daylight saving & the abbreviation caveat
"GMT" here means London's clock — GMT in winter, BST in summer. "CST" is really Central Time all year: CST in winter, CDT (Central Daylight Time) in summer, and locals just say CT. The US switches on March 8 and November 1, 2026, while London switches on March 29 and October 25. Because those dates differ, the gap is briefly off by an hour in late March and late October. The converter uses the correct offset for whatever date you enter, so a 5-hour result during one of those windows is expected, not wrong.
When you'll use it
Good for scheduling with teams in Chicago, Houston, or Dallas, tuning into a Central-time webinar, or planning a call with Mexico City. Central covers much of the US heartland, so it comes up often when London and America need to find a shared hour.
Frequently asked questions
How many hours behind London is US Central Time?
Six hours for most of the year. When it's 12:00 noon in London it's 6:00 AM in Chicago. The gap only shifts by an hour during the short windows when the US and UK clocks are out of step.
What's the difference between CST and CDT?
CST is the winter name; from mid-March to early November the Central US moves to Central Daylight Time (CDT). People there just call it Central Time, or CT, in either season.
When is the gap not exactly 6 hours?
During March 8–29 and October 25–November 1, 2026. The US and UK spring forward and fall back on different dates, so for those short stretches Central is 5 hours behind London instead of 6.