Highlighted rows fall within 09:00–18:00 in both places: 3 shared working hours.
How many hours is GMT ahead of CST?
As abbreviations, CST is always 6 hours behind of GMT: GMT is UTC+0 and CST is UTC−6. To convert, subtract 6 hours.
When the GMT to CST time difference changes
For most of the year CST is 5 hours behind of GMT. From 1 November to 31 December 2026, CST is 6 hours behind of GMT instead, because the two places change their clocks on different dates. Meetings booked by the usual gap land an hour off in those weeks.
Dates
CST vs GMT
Length
1 November 2026 to 31 December 2026
6 hours behind
61 days
1 January 2027 to 13 March 2027
6 hours behind
72 days
14 March 2027 to 6 November 2027
5 hours behind
238 days
7 November 2027 to 31 December 2027
6 hours behind
55 days
Calling hours for GMT and CST
When CST is 5 hours behind of GMT: 3 shared office hours, 14:00 to 17:00 in GMT (09:00 to 12:00 in CST).
When CST is 6 hours behind of GMT: 2 shared office hours, 15:00 to 17:00 in GMT (09:00 to 11:00 in CST).
Frequently asked questions about GMT and CST time
How many hours ahead is CST of GMT?
CST (UTC−6) is 6 hours behind of GMT (UTC+0).
Does the time difference between GMT and CST change?
Yes. It is usually 5 hours behind, but changes when one side moves its clocks: 6 hours behind from 1 November to 31 December 2026; 6 hours behind from 1 January to 13 March 2027.