There is no overlap between 09:00–18:00 working days in these two places.
How many hours is CST behind ACST?
As abbreviations, ACST is always 15.5 hours ahead of CST: CST is UTC−6 and ACST is UTC+9:30. To convert, add 15.5 hours.
When the CST to ACST time difference changes
For most of the year ACST is 14.5 hours ahead of CST. From 1 November to 31 December 2026, ACST is 15.5 hours ahead of CST 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
ACST vs CST
Length
1 November 2026 to 31 December 2026
15.5 hours ahead
61 days
1 January 2027 to 13 March 2027
15.5 hours ahead
72 days
14 March 2027 to 6 November 2027
14.5 hours ahead
238 days
7 November 2027 to 31 December 2027
15.5 hours ahead
55 days
Calling hours for CST and ACST
When ACST is 14.5 hours ahead of CST: no shared 09:00 to 17:00 hours; try 17:00 in CST (07:30 in ACST).
When ACST is 15.5 hours ahead of CST: no shared 09:00 to 17:00 hours; try 17:00 in CST (08:30 in ACST).
Frequently asked questions about CST and ACST time
How many hours ahead is ACST of CST?
ACST (UTC+9:30) is 15.5 hours ahead of CST (UTC−6).
Does the time difference between CST and ACST change?
Yes. It is usually 14.5 hours ahead, but changes when one side moves its clocks: 15.5 hours ahead from 1 November to 31 December 2026; 15.5 hours ahead from 1 January to 13 March 2027.