Convert any time between GMT and CST, with a full 24-hour table and the hours when both sides are actually at work.

GMT to CST Time Converter

CST is 6 hours behind GMT. The UK and Ireland are currently on BST (UTC+1:00), and The US Central states are currently on CDT (UTC-5:00).

GMT
Greenwich Mean Time
01:04:42 PM
Sunday, October 11, 2026
UTC+1:00
-6:00
hours difference
⇆ Reverse
CST
Central Standard Time
07:04:42 AM
Sunday, October 11, 2026
UTC-5:00

Best Time to Call Between GMT and CST

Both zones are inside normal business hours between 3:00 PM and 5:00 PM GMT — that's 9:00 AM to 11:00 AM CST. That's a 2-hour window.

both at work GMT only CST only neither  —  hours along the strip are GMT.

GMT to CST: Full 24-Hour Conversion Table

Shaded rows are working hours; the darker shade marks the hours when both zones are at work.

GMTCSTWorking hours
12:00 AM 6:00 PM prev day —
1:00 AM 7:00 PM prev day —
2:00 AM 8:00 PM prev day —
3:00 AM 9:00 PM prev day —
4:00 AM 10:00 PM prev day —
5:00 AM 11:00 PM prev day —
6:00 AM 12:00 AM —
7:00 AM 1:00 AM —
8:00 AM 2:00 AM —
9:00 AM 3:00 AM GMT only
10:00 AM 4:00 AM GMT only
11:00 AM 5:00 AM GMT only
12:00 PM 6:00 AM GMT only
1:00 PM 7:00 AM GMT only
2:00 PM 8:00 AM GMT only
3:00 PM 9:00 AM Both zones
4:00 PM 10:00 AM Both zones
5:00 PM 11:00 AM CST only
6:00 PM 12:00 PM CST only
7:00 PM 1:00 PM CST only
8:00 PM 2:00 PM CST only
9:00 PM 3:00 PM CST only
10:00 PM 4:00 PM CST only
11:00 PM 5:00 PM —

What GMT and CST Actually Are

GMT — Greenwich Mean Time

The UK and Ireland in winter, plus Iceland, Portugal and much of West Africa. Standing at UTC as written, and the region does change its clocks, so its live offset moves by an hour twice a year. The next change is on Sunday, October 25, 2026, to GMT. Often used loosely as a synonym for UTC. They differ by less than a second, so for scheduling they are interchangeable.

Britain ran an experiment from 1968 to 1971 on permanent UTC+1, abandoning GMT entirely. It was scrapped after complaints about dark winter mornings in Scotland.

CST — Central Standard Time

Chicago, Houston, Dallas, Mexico City, Winnipeg. Standing at UTC-6:00 as written, and the region does change its clocks, so its live offset moves by an hour twice a year. The next change is on Sunday, November 1, 2026, to CST. CST also stands for China Standard Time (UTC+8) and Cuba Standard Time (UTC-5). This page covers the North American one.

Saskatchewan sits inside the Central zone but never changes its clocks, so it matches CST in winter and its neighbors' MDT in summer.

What This Means in Practice

Both sides change clocks, on different dates

Both regions observe daylight saving but do not switch on the same day, so for a week or two each spring and fall the gap between them is an hour different from the rest of the year. Those short windows are where recurring invitations quietly break.

Frequently Asked Questions

What is the time difference between GMT and CST?

CST is 6 hours behind GMT.

What is 9:00 AM GMT in CST?

9:00 AM GMT is 3:00 AM CST.

What are the best hours to schedule a call between GMT and CST?

Between 3:00 PM and 5:00 PM GMT, which is 9:00 AM to 11:00 AM CST. Both sides are inside normal business hours through that window.

Does the difference between GMT and CST change during the year?

Yes. Both regions observe daylight saving, and they do not switch on the same dates, so the gap shifts by an hour at least twice a year. The next clock change is on Sunday, October 25, 2026.

Does GMT always mean Greenwich Mean Time?

Often used loosely as a synonym for UTC. They differ by less than a second, so for scheduling they are interchangeable.

Does CST always mean Central Standard Time?

CST also stands for China Standard Time (UTC+8) and Cuba Standard Time (UTC-5). This page covers the North American one.

Converting between two time zones regularly? Bookmark this page — the clocks update live and the table follows daylight saving automatically.