CST to GMT Converter

Central Standard Time is UTC−6 and Central Daylight Time is UTC−5. GMT, as this page uses it, is the fixed UTC+0 reference with no summer time, listed as Etc/GMT in the IANA time zone database. So the gap is six hours in the US winter and five in the US summer.

The Central zone moves forward at 2:00 AM on the second Sunday in March and back at 2:00 AM on the first Sunday in November, as the US Department of Transportation describes. Here are the exact periods:

Flight plans, shipping cut-offs and many international filings use GMT or UTC. If a form must be in by 23:59 GMT, the last Central-time moment is 5:59 PM CST in winter or 6:59 PM CDT in summer. Midnight GMT falls in the late afternoon or early evening in Chicago, not at night.

Going the other way, a GMT time minus six hours (or five in summer) gives Central time. Noon GMT is 6:00 AM in Dallas in winter and 7:00 AM in summer, which is why broadcasts timed for the middle of the European day reach Texas at breakfast.

For live calls with people in the UK, remember that London itself shifts to BST from late March to late October. In summer, London is six hours ahead of Chicago rather than five, except during the short weeks in March and October when only one side has changed.