CST: which one do you mean?
CST means 3 different things, and they are hours apart. If you received a timestamp labelled CST, the sender's location decides which of these applies, so pick it below.
Central Standard Time · North America
20:45:49
Saturday, 26 September 2026
- abbreviation denotes
- -06:00
- in force right now
- CDT (UTC-05:00) · DST
- use in code
- America/Chicago
- also valid
- America/Winnipeg, America/Mexico_City
- next clock change
- 1 Nov 2026 01:00 → CST
US and Canadian midwest, winter half of the year.
Right now this zone is on CDT, not CST. They are the same place at different times of year.
China Standard Time · Asia
09:45:49
Sunday, 27 September 2026
- abbreviation denotes
- +08:00
- in force right now
- CST (UTC+08:00)
- use in code
- Asia/Shanghai
- also valid
- Asia/Macau
- next clock change
- none, fixed offset
All of mainland China runs on this single zone.
Cuba Standard Time · Caribbean
21:45:49
Saturday, 26 September 2026
- abbreviation denotes
- -05:00
- in force right now
- CDT (UTC-04:00) · DST
- use in code
- America/Havana
- next clock change
- 1 Nov 2026 00:00 → CST
Cuba observes daylight saving as CDT (UTC-4).
Right now this zone is on CDT, not CST. They are the same place at different times of year.
Use the IANA name, not the abbreviation
Python
from datetime import datetime
from zoneinfo import ZoneInfo
# right: an IANA zone carries the full history of rule changes
now = datetime.now(ZoneInfo("America/Chicago"))
print(now.isoformat(), now.tzname())
# wrong: an abbreviation is not resolvable, and a hard-coded offset
# silently rots the next time the rules change
# now = datetime.now(timezone(timedelta(hours=...))) # don'tCST questions
What does CST stand for?
CST has 3 distinct meanings in active use: Central Standard Time (-06:00, America/Chicago); China Standard Time (+08:00, Asia/Shanghai); Cuba Standard Time (-05:00, America/Havana). Which one applies depends entirely on who wrote the timestamp.
What time is it in CST right now?
Central Standard Time: 20:45 on Saturday (CDT); China Standard Time: 09:45 on Sunday (CST); Cuba Standard Time: 21:45 on Saturday (CDT).
Which IANA timezone should I use instead of CST?
America/Chicago for Central Standard Time, Asia/Shanghai for China Standard Time, America/Havana for Cuba Standard Time. Date libraries cannot resolve bare abbreviations, and an abbreviation carries no daylight-saving history, so a stored offset silently rots when a government changes the rules.
Why does my computer show CDT instead of CST?
Because America/Chicago is currently on CDT (UTC-05:00), its daylight-saving variant. CST (-06:00) applies during the other half of the year. Both names refer to the same place, one hour apart.