What time in Australia when us market opens?

The US Market opens at 9:30am Eastern Time which is 14:30 UTC (Greenwich Mean Time).

To convert to Australian time - take 14:30 and add in the appropriate offset depending on what part of Australia you are in.

CDT Central Daylight Time UTC + 10:30 hours

CST Central Standard Time UTC + 9:30 hours

CXT Christmas Island Time UTC + 7 hours

EDT Eastern Daylight Time UTC + 11 hours

EST Eastern Standard Time UTC + 10 hours

LHDT Lord Howe Daylight Time UTC + 11 hours

LHST Lord Howe Standard Time UTC + 10:30 hours

NFT Norfolk Time UTC + 11:30 hours

WDT Western Daylight Time UTC + 9 hours

WST Western Standard TimeUTC + 8 hours

For example, Sydney is in EST, so the market would open at 14:30 + 10 = 02:30+1day. That is the Monday morning market would open at 2:30am Tuesday Sydney time.

Note that you will need to track the dates for Daylight Savings time in both Australia and the USA as they will change at different times during the year.