GMT to ACST Converter

Standard business hours (9 AM–5 PM, Mon–Fri) in Greenwich Mean Time and Australian Central Time don't overlap on the same weekday. Australian Central Time is 9 hours ahead of Greenwich Mean Time.

With some flexibility, there’s a workable window outside standard hours:

• 7 AM–12 PM in Greenwich Mean Time (3 PM–8 PM in Australian Central Time) — suggest 9:00 AM Greenwich Mean Time (5:30 PM Australian Central Time).

This means an early start or late finish for one side, but it’s a reasonable slot for a one-off meeting.

Greenwich Mean Time is also known as GMT, or BST. To call United Kingdom, dial +44.

Australian Central Time is also known as ACST, or ACDT. To call Australia, dial +61.

Australian Central Time is approximately 10,100 miles east of Greenwich Mean Time.

Both zones observe daylight saving time, but they transition on different dates.

Greenwich Mean Time: next transition on Sunday, October 25, 2026.

Australian Central Time: next transition on Sunday, October 4, 2026.

Greenwich Mean Time and Australian Central Time are in opposite hemispheres, so their clocks change in opposite directions about six months apart — one springs forward while the other falls back. The offset between them therefore shifts twice a year and can swing by up to two hours across the seasons, more than a typical same-hemisphere pair. Recurring meetings will need re-checking after each transition.

See the daylight saving time page for transition dates across every time zone.