GMT to CST Converter: GMT to Central Time

GMT is UTC+0, all year, with no daylight saving time. Central Time is CST (UTC−6) in standard time and CDT (UTC−5) during daylight saving time. DateMath reads both clocks for the date you pick, so the answer always uses the names and offsets in force that day.

Because only one of the zones changes its clocks, the difference changes during the year. A converter or a rule of thumb with one fixed number is wrong for part of the year; the table below gives the dates for 2027.

Every hour of the day in GMT, read in Central Time. The two columns are January 15, 2027 and July 15, 2027, standard and daylight saving time.

GMT or UK time?

This page converts GMT as UTC+0, the same all year. London uses GMT only in winter: from the last Sunday in March to the last Sunday in October it is on BST, UTC+1, an hour later. If you mean the time in the UK, pick UK time in the converter; in summer it is 5 hours ahead of Eastern Time and 6 ahead of Central Time, except in the weeks when the US and the UK change their clocks on different dates.

Turn the difference around: Central Time to GMT on each date uses the same gap in the other direction. Press Swap in the converter above to switch the two zones.

With both sides working 9 to 5, the shared hours are 3:00 PM to 5:00 PM GMT in GMT, 9:00 AM to 11:00 AM CST in Chicago in winter and 2:00 PM to 5:00 PM GMT in GMT, 9:00 AM to 12:00 PM CDT in Chicago in summer. To add more people or other working hours, use the meeting planner. For an event set at a time in Central Time, convert it here, then count down to it with the day countdown.

DateMath turns the date and time you enter into one moment on the from zone's clock, then reads that moment on every other zone's clock, with each zone's UTC offset for that exact date from the IANA time zone database in your browser. So the difference between two zones is worked out for the date you pick, never taken from a fixed table: Pacific Time is 3 hours behind Eastern Time all year, but UTC is 8 hours ahead of Pacific Time in winter and 7 in summer.

• The IANA time zone database. DateMath's time zone tools take each zone's UTC offset and daylight saving dates from the IANA time zone database (tz) built into your browser, the data computers and phones set their clocks by, so every date gets the rule in force on it. US daylight saving time runs from 2:00 AM on the second Sunday in March to 2:00 AM on the first Sunday in November (15 U.S.C. 260a); the EU and the UK change at 1:00 AM UTC on the last Sundays of March and October. Source: IANA time zones, 15 U.S.C. 260a, Directive 2000/84/EC.
• The Gregorian calendar. DateMath treats every date as a Gregorian date, with its leap-year rule: a year divisible by 4 is a leap year, except century years not divisible by 400, so 2000 had a February 29 and 2100 will not. Source: Gregorian calendar.

DateMath's date math is tested against more than 100 cases worked out by hand. Every worked example and table on the site is computed with the same code the calculators run, so a page and its calculator can't disagree.