CST to AST: CST is 2 hours behind AST
Central Time is 2 hours behind Atlantic Time, on every day of the year. It is 10:21 pm CDT in Central and 12:21 am ADT in Atlantic, which is already the next day there.
Convert a specific time from CST to AST
Pick any time and date to convert it both ways. The conversion runs in your browser against the real zone rules, so a date inside a daylight saving period gets that period's offset rather than today's.
What is the time difference between CST and AST?
Atlantic Time is 2 hours ahead of Central Time. To go from CST to AST you add 2 hours. That gap holds on all 365 days of 2026: both zones move their clocks, but on the same dates and in the same direction, so the distance between them never changes.
CST to AST conversion table
Every hour of Thursday, September 24, 2026 in Central, with the matching reading in Atlantic. 2 of the 24 hours land on a different calendar date in Atlantic, which is the part people get wrong when they schedule across this pair.
| CST | CST 24h | AST | AST 24h | Date |
|---|---|---|---|---|
| 12:00 am | 00:00 | 2:00 am | 02:00 | same day |
| 1:00 am | 01:00 | 3:00 am | 03:00 | same day |
| 2:00 am | 02:00 | 4:00 am | 04:00 | same day |
| 3:00 am | 03:00 | 5:00 am | 05:00 | same day |
| 4:00 am | 04:00 | 6:00 am | 06:00 | same day |
| 5:00 am | 05:00 | 7:00 am | 07:00 | same day |
| 6:00 am | 06:00 | 8:00 am | 08:00 | same day |
| 7:00 am | 07:00 | 9:00 am | 09:00 | same day |
| 8:00 am | 08:00 | 10:00 am | 10:00 | same day |
| 9:00 am | 09:00 | 11:00 am | 11:00 | same day |
| 10:00 am | 10:00 | 12:00 pm | 12:00 | same day |
| 11:00 am | 11:00 | 1:00 pm | 13:00 | same day |
| 12:00 pm | 12:00 | 2:00 pm | 14:00 | same day |
| 1:00 pm | 13:00 | 3:00 pm | 15:00 | same day |
| 2:00 pm | 14:00 | 4:00 pm | 16:00 | same day |
| 3:00 pm | 15:00 | 5:00 pm | 17:00 | same day |
| 4:00 pm | 16:00 | 6:00 pm | 18:00 | same day |
| 5:00 pm | 17:00 | 7:00 pm | 19:00 | same day |
| 6:00 pm | 18:00 | 8:00 pm | 20:00 | same day |
| 7:00 pm | 19:00 | 9:00 pm | 21:00 | same day |
| 8:00 pm | 20:00 | 10:00 pm | 22:00 | same day |
| 9:00 pm | 21:00 | 11:00 pm | 23:00 | same day |
| 10:00 pm | 22:00 | 12:00 am | 00:00 | the next day |
| 11:00 pm | 23:00 | 1:00 am | 01:00 | the next day |
What are the best hours to schedule a call between CST and AST?
6 hours of the standard 9:00 am to 5:00 pm working day line up in both zones, from 9:00 am CST to 3:00 pm CST. In Atlantic that window reads 11:00 am to 5:00 pm. Outside it, one side is either not yet at their desk or already gone.
| CST | AST | Working hours | Note |
|---|---|---|---|
| 9:00 am | 11:00 am | both sides | mid morning in Central, mid morning in Atlantic |
| 10:00 am | 12:00 pm | both sides | mid morning in Central, noon in Atlantic |
| 11:00 am | 1:00 pm | both sides | mid morning in Central, afternoon in Atlantic |
| 12:00 pm | 2:00 pm | both sides | noon in Central, afternoon in Atlantic |
| 1:00 pm | 3:00 pm | both sides | afternoon in Central, afternoon in Atlantic |
| 2:00 pm | 4:00 pm | both sides | afternoon in Central, afternoon in Atlantic |
Does daylight saving change CST to AST?
Central Time is currently on CDT and changes next on Sunday, November 1, 2026, when the clock falls back from 1:59 am to 1:00 am and the offset moves from UTC-5 to UTC-6.
Atlantic Time is currently on ADT and changes next on Sunday, November 1, 2026, when the clock falls back from 1:59 am to 1:00 am and the offset moves from UTC-3 to UTC-4.
Is CST ahead of or behind AST?
CST is behind AST by 2 hours: when it is 12:00 pm in Central, it is 2:00 pm in Atlantic. One wrinkle worth knowing: CST and CDT are two names for the same zone, not two zones. Central Time reads CST in winter and CDT in summer. When somebody types "cst to ast" they nearly always mean the zone rather than the literal winter offset, so this page resolves CST to America/Chicago and AST to America/Halifax and applies whichever offset is genuinely in force on the day.
Central Time covers Chicago, Dallas, Houston and Winnipeg. Atlantic Time covers Halifax, Moncton and the Canadian Maritimes. The identifiers behind them are America/Chicago and America/Halifax, which is what any calendar or scheduling system should be storing rather than a fixed number of hours.
Questions
- What is CST in AST?
- CST is 2 hours behind AST. 9:00 am CST is 11:00 am AST.
- How many hours ahead is AST of CST?
- AST is 2 hours ahead of CST.
- What time is it in Atlantic right now?
- 12:21 am ADT on Friday, September 25, 2026.
- When can Central and Atlantic meet during working hours?
- Between 9:00 am and 3:00 pm CST, which is 11:00 am to 5:00 pm AST.
- Does this account for daylight saving?
- Yes. Every reading is computed from the IANA database for the actual date, so CDT and ADT are the abbreviations genuinely in force today rather than a fixed assumption.
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