Highlighted rows fall within 09:00–18:00 in both places: 4 shared working hours.
How many hours is CET ahead of AST?
As abbreviations, AST is always 5 hours behind of CET: CET is UTC+1 and AST is UTC−4. To convert, subtract 5 hours.
When the CET to AST time difference changes
For most of the year AST is 6 hours behind of CET. From 25 October to 31 December 2026, AST is 5 hours behind of CET 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
AST vs CET
Length
25 October 2026 to 31 December 2026
5 hours behind
68 days
1 January 2027 to 27 March 2027
5 hours behind
86 days
28 March 2027 to 30 October 2027
6 hours behind
217 days
31 October 2027 to 31 December 2027
5 hours behind
62 days
Best time for a meeting between CET and AST
When AST is 6 hours behind of CET: 2 shared office hours, 15:00 to 17:00 in CET (09:00 to 11:00 in AST).
When AST is 5 hours behind of CET: 3 shared office hours, 14:00 to 17:00 in CET (09:00 to 12:00 in AST).
Frequently asked questions about CET and AST time
How many hours ahead is AST of CET?
AST (UTC−4) is 5 hours behind of CET (UTC+1).
Does the time difference between CET and AST change?
Yes. It is usually 6 hours behind, but changes when one side moves its clocks: 5 hours behind from 25 October to 31 December 2026; 5 hours behind from 1 January to 27 March 2027.